v19.10: (Upcoming Release)

bdev zone

Added new public header for zoned bdev. Zoned bdev is an extension of the bdev interface.

spdk_bdev_get_zone_size(), spdk_bdev_get_max_open_zones(), spdk_bdev_get_optimal_open_zones() APIs were added for retrieving zoned device information. spdk_bdev_get_zone_info() API was added for retrieving information about zones in zoned device. Added spdk_bdev_zone_management() API for changing zone state. spdk_bdev_zone_append() and spdk_bdev_zone_append_with_md() APIs were added for appending data to a zone. Added spdk_bdev_io_get_append location() function for retrieving append location for I/O.


Added spdk_bdev_get_write_unit_size() function for retrieving required number of logical blocks for write operation.

New zone-related fields were added to the result of the get_bdevs RPC call:

  • zoned: indicates whether the device is zoned or a regular block device
  • zone_size: number of blocks in a single zone
  • max_open_zones: maximum number of open zones
  • optimal_open_zones: optimal number of open zones The zoned field is a boolean and is always present, while the rest is only available for zoned bdevs.


The spdk_nvmf_tgt_create function now accepts an object of type spdk_nvmf_target_opts as its only parameter. This new structure contains the max_subsystems parameter previously passed into that function.

A new public API function spdk_nvmf_get_tgt has been added which allows users to retrieve a pointer to an spdk_nvmf_tgt object by supplying its name. In the special case where an RPC or application only creates a single target, this function can accept a null name parameter and will return the only available target.

The majority of the NVMe-oF RPCs now accept an optional tgt_name parameter. This will allow those RPCs to work with applications that create more than one target.

Three new NVMe-oF RPCs have been added nvmf_create_target, nvmf_delete_target, and nvmf_get_targets. These new RPCs provide a basic interface for managing multiple target objects. In SPDK the target object defines a unique discovery service. As of this release, these RPCs are not intended to be used with the in-tree SPDK target applications, spdk_tgt and nvmf_tgt, which use a single, global target structure. As such, they are not included in scripts/

Three new header functions have also been added to help deal with multiple targets. spdk_nvmf_tgt_get_name takes a target pointer as an argument and returns its human readable name. spdk_nvmf_get_first_target takes no arguments and returns the first target in the global list. spdk_nvmf_get_next_tgt takes a target pointer as an argument and returns the next one in the global list.


A new spdk_bdev_open_ext function has been added and spdk_bdev_open function has been deprecated. The new open function introduces requirement to provide callback function that will be called by asynchronous event such as bdev removal. spdk_bdev_open_ext function takes bdev name as an argument instead of bdev structure to avoid a race condition that can happen when the bdev is being removed between a call to get its structure based on a name and actually openning it.

New 'resize' event has been added to notify about change of block count property of block device. Event is delivered only if block device was opened with spdk_bdev_open_ext function.


A new spdk_bdev_create_bs_dev_from_desc function has been added and spdk_bdev_create_bs_dev function has been deprecated. The new create function can cowork with spdk_bdev_open_ext function, which provides callback function that will be called by asynchronous event such as bdev removal.


A new blobfs module bdev has been added to simplify the operations of blobfs on bdev.

Function spdk_blobfs_bdev_detect is added to detect whether blobfs exists on the given block device.

Function spdk_blobfs_bdev_create is added to create a blobfs on the given block device.


Option to build FUSE components into blobfs_bdev module for mounting a blobfs filesystem. It requires the installation of libfuse3. By default, it is disabled. And it will be enabled if run ./configure with --with-fuse option.


Added no_shn_notification to NVMe controller initialization options, users can enable it for NVMe controllers. When the option is enabled, the controller will not do the shutdown process and just disable the controller, users can start their application later again to initialize the controller to the ready state.

A controller flag SPDK_NVME_CTRLR_WRR_SUPPORTED was added to indicate the controller can support weighted round robin arbitration feature with submission queue.

Added arbitration_burst option for arbitration feature, and added three low/medium/high_priority_weight options for weighted round robin arbitration.

Added spdk_nvme_ns_cmd_write_uncorrectable.


Portals may no longer be associated with a cpumask. The scheduling of connections is moving to a more dynamic model.

An new RPC iscsi_portal_group_set_auth has been added to set CHAP authentication for discovery sessions specific for the existing iSCSI portal group. This RPC overwrites the setting by the global parameters for the iSCSI portal group.

delay bdev

The bdev_delay_update_latency has been added to allow users to update a latency value for a given delay bdev.

compress bdev

A new RPC bdev_compress_get_orphans has been added to list compress bdevs that were not loaded due to a missing pm metadata file. In this state they can only be deleted.

null bdev

Metadata support has been added to Null bdev module.

Protection information support has been added to Null bdev module.


start_subsystem_init RPC no longer stops the application on error during initialization.


Added optional parameters '–arbitration-burst' and '–low/medium/high-priority-weight' to 'bdev_nvme_set_options' RPC method.

Added optional parameter '–md-size' to 'construct_null_bdev' RPC method.

Added optional parameters '–dif-type' and '–dif-is-head-of-md' to 'construct_null_bdev' RPC method.

Added blobfs_detect RPC method to detect whether a blobfs exists on given bdev.

Added blobfs_create RPC method to build blobfs on given bdev.



EXPERIMENTAL: Added ability to mirror writes to persistent write buffer cache to allow for recovery from dirty shutdown event.

Added handling of Asynchronous Nand Management Events (ANM).


EXPERIMENTAL: Added Intel Volume Management Device (VMD) driver. VMD is an integrated controller inside the CPU PCIe root complex. It enables virtual HBAs for the connected NVMe SSDs. spdk_vmd_init() enumerates NVMe SSDs behind VMD device and hook them into SPDK PCI subsystem. spdk_nvme_probe() or spdk_nvme_connect() can be used to connect NVMe driver to the device located at the given transport ID.

To obtain transport ID of NVMe SSD behind VMD spdk_lspci can be used.

Current implementation does not support hotplug.


Blobfs file asynchronous operations were added to public APIs.


A new file API spdk_posix_file_load was added to load file content into a data buffer.

New APIs spdk_dif_ctx_set_data_offset, spdk_dif_verify_stream, spdk_dif_get_range_with_md, spdk_dif_get_length_with_md have been added, and existing APIs spdk_dif_ctx_init, spdk_dif_set_md_interleave_iovs, and spdk_dif_generate_stream have been refined to insert or strip DIF by stream fasion with any alignment.

New APIs spdk_dif_ctx_set_remapped_init_ref_tag, spdk_dif_remap_ref_tag, and spdk_dix_remap_ref_tag have been added to remap DIF reference tag.

New APIs spdk_dif_update_crc32c and spdk_dif_update_crc32c_stream have been added to compute CRC-32C checksum for extended LBA payload.

Bdevperf and bdevio applications now support starting tests with application specific RPCs. Please see helper Python scripts in their respective directories. This is a move towards simpler RPC-only configuration for all main and auxiliary applications.

Legacy INI style configuration for SPDK applications will become deprecated in SPDK 19.10, and removed in SPDK 20.01. Please consider moving to JSON-RPC configuration files and/or RPC driven run-time configuration.


EXPERIMENTAL: A Fibre Channel transport that supports Broadcom HBAs has been added. This depends on the FC HBA driver at See the documentation for more information.

Persistent reservation emulation has been added to the NVMe-oF target. Persistent reservation state is stored in a JSON file on the local filesystem between target restart. To support this, an optional parameter to the RPC method nvmf_subsystem_add_ns called --ptpl-file was added. This allows the user to specify which file to store the persistent reservation state in. Note that this is done per namespace.

The c2h success optimization under which a command capsule response is not sent for reads is turned on by default. A config knob was added to allow disabling the optimization. This will mostly be used for integration testing with 5.0.x kernels while some compatibility fixes make their way down the pipeline for 5.1.x kernels.

The sock priority setting of the TCP connection owned by the tcp transport is added. It is used to optimize the TCP connection performance under designated traffic classes. And the priority is used to differeniate the sock priority between SPDK NVMe-oF TCP target application and other TCP based applications.

Shared receive queue can now be disabled even for NICs that support it using the nvmf_create_transport RPC method parameter no_srq. The actual use of a shared receive queue is predicated on hardware support when this flag is not used.

spdk_nvmf_get_optimal_poll_group was added, which is used to return the optimal poll group for the qpair. And ConnectionScheduler configuration is added into the [Nvmf] section in etc/spdk/ to demonstrate how to configure the connection scheduling strategy among different spdk threads.

Added infrastructure to retrieve global and per poll group NVMf statistics.

DIF strip and insert is now supported for TCP transport. When it is enabled, DIF setting is not exposed to the NVMe-oF initiator, and DIF is attached into data for write I/O and stripped from data for read I/O.

Added a field dif_insert_or_strip to struct spdk_nvmf_transport_opts, and updated the related rpc function nvmf_create_transport to make this configurable parameter available to users. The dif_insert_or_strip is relevant for TCP transport for now and used to configure the DIF strip and insert.

Added infrastructure to retrieve NVMf transport statistics.


The function spdk_notify_get_types() and spdk_notify_get_events() were renamed to spdk_notify_foreach_type() and spdk_notify_foreach_event(), respectively. And update type name of callback accordingly.


The format of the data returned by the get_bdevs_iostat RPC has changed to make it easier to parse. It now returns an object with a "ticks" object and "bdevs" array with the per-bdev statistics.

A new bdev module delay has been added which simulates a drive latency when placed on top of a Null bdev. This module is intended only for testing and can be created using the new RPC bdev_delay_create. That RPC takes the name of the underlying bdev as well as average and p99 latency arguments for both read and write operations. Average latency is defined as a value close to what you would expect a perf tool such as FIO to report back as the mean latency of all I/O submitted to the drive. p99 latency is defined as the value one would expect the drive to see the slowest 1% of I/O report. For underlying drives with already significant latency, the latency values provided to the drive will be additive. This should be taken into account if trying to achieve an artificial latency on top of an nvme drive or aio device.

DIF reference tag remapping is now supported for partition type virtual bdev modules. When using partition type virtual bdevs, block address space is remapped during I/O processing and DIF reference tag is remapped accordingly.

Added spdk_bdev_*_with_md() functions allowing for IO with metadata being transferred in separate buffer. To check support for separatate metadata, use spdk_bdev_is_md_separate().

All bdevs now have a UUID. For devices whose backing hardware does not provide a UUID, one is automatically generated. Across runs of SPDK, bdevs whose UUID is automatically generated may change.

A new virtual bdev module compress has been added to provide compression services on top of a thinly provisioned logical volume. See documentation for complete details.


Added an optional parameter --io-queue-requests to RPC set_bdev_nvme_options, which can be used to change the number of requests allocated for one NVMe I/O queue. For very big I/O size, e.g. 128MiB, with this option user will not get an error due to limited requests in NVMe driver layer.

Added spdk_nvme_ctrlr_get_transport_id() to get the transport ID from a previously attached controller.

Nvme Opal library spdk_opal_cmd deprecated. Adding seperate command APIs. NVMe Opal library add support for activating locking SP which will make the transaction from "Manufactured-Inactive" state to "Manufactured" state. Upon successfully invoking of this method, lock and unlock features will be enabled. NVMe Opal library add support for locking/unlocking range and list locking range info. NVMe opal library add support for multiuser. Admin can enable user and add user to specific locking range and the user can lock/unlock his range.

Added spdk_nvme_ctrlr_io_cmd_raw_no_payload_build() allowing a caller to pass a completely formed command to an NVMe submission queue (buffer addresses and all). This is supported on the PCIe transport only.

Added spdk_nvme_get_ctrlr_registers() to return a pointer to the virtual address of the NVMe controller registers. This is supported on the PCIe transport only.

Added additional options to the spdk_nvme_ctrlr_alloc_qpair() option parameter structure to allow caller to override the virtual and optionally physical address of the submission and completion queue pair to be created. This is supported on the PCIe transport only.

Added disable_error_logging to struct spdk_nvme_ctrlr_opts, which disables logging of failed requests. By default logging is enabled.

Added spdk_nvme_qpair_print_command(), spdk_nvme_qpair_print_completion() and spdk_nvme_cpl_get_status_string(). Allowing for easier display of error messages.

Added support for NVMe Sanitize command.


The parameter free_space has been added to spdk_ring_enqueue() to wait when the ring is almost full and resume when there is enough space available in the ring.

A new API spdk_mempool_lookup has been added to lookup the memory pool created by the primary process.

Added spdk_pci_get_first_device() and spdk_pci_get_next_device() to allow iterating over PCI devices detected by SPDK. Because of this, all SPDK APIs to attach/detach PCI devices are no longer thread safe. They are now meant to be called from only a single thread only, the same only that called spdk_env_init(). This applies to the newly added APIs as well.


SPDK now supports VPP version 19.04.2, up from VPP 18.01.

VPP socket abstraction now uses VPP Session API, instead of VLC (VPP Communications Library). This allows for better control over sessions and queues. Please see VPP documentation for more details: VPP Host Stack


Add spdk_sock_get_optimal_sock_group(), which returns the optimal sock group for this socket. When a socket is created, it is often assigned to a sock group using spdk_sock_group_add_sock so that a set of sockets can be polled more efficiently. For some network devices, it is optimal to assign particular sockets to specific sock groups. This API is intended to provide the user with that information.

spdk_sock_group_get_ctx() was added to return the context of the spdk_sock_group. spdk_sock_group_create() is updated to allow input the user provided ctx. spdk_sock_set_priority() is added to set the priority of the socket.


Added thread_get_stats RPC method to retrieve existing statistics.

Added nvmf_get_stats RPC method to retrieve NVMf susbsystem statistics.

Response buffers for RPC requests are now always pre-allocated, which implies that all spdk_jsonrpc_begin_result() calls always succeed and return a valid buffer for JSON response. RPC calls no longer need to check if the buffer is non-NULL.

Added SPDK_RPC_REGISTER_ALIAS_DEPRECATED to help with deprecation process when renaming existing RPC. First time a deprecated alias is used, it will print a warning message.

RPC get_rpc_methods was renamed rpc_get_methods. The old name is still usable, but is now deprecated.


A snapshot can now be deleted if there is only a single clone on top of it.


Preliminary support for cross compilation is now available. Targeting an older CPU on the same architecture using your native compiler can be accomplished by using the --target-arch option to configure as follows:

./configure --target-arch=broadwell

Additionally, some support for cross-compiling to other architectures has been added via the --cross-prefix argument to configure. To cross-compile, set CC and CXX to the cross compilers, then run configure as follows:

./configure --target-arch=aarm64 --cross-prefix=aarch64-linux-gnu


A security vulnerability has been identified and fixed in SPDK Vhost-SCSI target. A malicious client (e.g. a virtual machine) could send a carefully prepared, invalid I/O request to crash the entire SPDK process. All users of SPDK Vhost-SCSI target are strongly recommended to update. All SPDK versions < 19.07 are affected.

By default, SPDK will now rely on upstream DPDK's rte_vhost instead of its fork located inside SPDK repo. The internal fork is still kept around to support older DPDK versions, but is considered legacy and will be eventually removed.

configure will now automatically use the upstream rte_vhost if the used DPDK version is >= 19.05.

spdk_vhost_init() is now asynchronous and accepts a completion callback.

iscsi target

A security vulnerability has been identified and fixed in SPDK iSCSI target. A malicious client (e.g. an iSCSI initiator) could send a carefully prepared, invalid I/O request to crash the entire SPDK process. All users of SPDK iSCSI target are strongly recommended to update. All SPDK versions < 19.07 are affected.


Exposed spdk_set_thread() in order for applications to associate with SPDK thread when necessary.

Added spdk_thread_destroy() to allow framework polling the thread to release resources associated with that thread.



Added asynchronous probe support. New APIs spdk_nvme_probe_async(), spdk_nvme_connect_async() and spdk_nvme_probe_poll_async() were added to enable this feature. spdk_nvme_probe_async() and spdk_nvme_connect_async() return a context associated with the specified controllers. Users then call spdk_nvme_probe_poll_async() until it returns 0, indicating that the operation completed.

A new qpair creation option, delay_pcie_doorbell, was added. This can be passed to spdk_nvme_alloc_io_qpair(). This makes the I/O submission functions, such as spdk_nvme_ns_writev(), skip ringing the submission queue doorbell. Instead the doorbell will be rung as necessary inside spdk_nvme_qpair_process_completions(). This can result in significantly fewer MMIO writes to the doorbell register under heavy load, greatly improving performance.

spdk_nvme_ctrlr_get_regs_cmbsz() was added to report the size of the controller memory buffer, if available.

spdk_nvme_ctrlr_get_flags() was added to return controller feature flags. Two flags are currently tracked: SPDK_NVME_CTRLR_SGL_SUPPORTED SPDK_NVME_CTRLR_SECURITY_SEND_RECV_SUPPORTED

The NVMe hotplug poller is now able to detach devices hot-removed from the system via /sys/bus/pci/devices/<bdf>/remove and /sys/bus/pci/devices/<bdf>/driver/unbind.

Opal support was added for scan, take ownership, revert TPer, and dumping device info. The nvme_manage tool can be used to perform these operations. The public API functions are spdk_nvme_ctrlr_security_receive() and spdk_nvme_ctrlr_security_send(). This module should be considered experimental pending additional features and tests.

The NVMe-oF initiator is now able to transfer IO whose size is more than 128KiB if the corresponding NVMe-oF target allows.


Added new strip_size_kb rpc param on create to replace the more ambiguous strip_size. The strip_size rpc param is deprecated.

Changed the raid bdev product_name from "Pooled Device" to "Raid Volume"


Added spdk_thread_has_pollers() function to verify if there are any registered pollers to be run on the thread. Added spdk_thread_is_idle() function to check if there are any scheduled operations to be performed on the thread at given time.

spdk_thread_create() now takes an optional CPU affinity mask that is passed to the scheduler.

spdk_thread_lib_init() now takes an optional context size. For each thread created, an additional region of memory of this size will be allocated. A pointer to this region of memory can be obtained by calling spdk_thread_get_ctx(). The inverse operation is also available via spdk_thread_get_from_ctx().

spdk_thread_poll() now optionally accepts the current time, in ticks. This can be used to avoid some calls to spdk_get_ticks() internally.

spdk_app_start() now only accepts a single context argument.


An new API spdk_bdev_get_data_block_size has been added to get size of data block except for metadata.

spdk_vbdev_register() has been deprecated. spdk_bdev_register() should be used instead.

A mechanism for acquiring and releasing data buffers from bdev modules, used to perform zero copy operations, was added.

New APIs spdk_bdev_get_md_size(), spdk_bdev_is_md_interleaved(), spdk_bdev_get_dif_type(), spdk_bdev_is_dif_head_of_md(), and spdk_bdev_is_dif_check_enabled() have been added to get metadata and DIF settings.

Bdevs claimed by the examine_config callback will be now further examined in the examine_disk callback.

spdk_bdev_io_get_io_channel() was added as a convenient way to get an io_channel from a bdev_io.


Updated OCF submodule to OCF v19.3.2

Added support for many-to-one configuration for OCF bdev. Multiple core devices can now be cached on single cache device.

Added persistent metadata support, allowing to restore cache state after shutdown. During start of SPDK application, the devices are examined and if OCF metadata is present - appropriate OCF bdevs will be recreated.

Added Write-Back mode support. In this mode, data is first written to caching device and periodically synchronized to the core devices. Dirty data is saved as persistent metadata on cache device, allowing for safe restore during application restart. For more details please see OCF documentation: OpenCAS cache configuration

NVMe-oF Target

Support for per-device shared receive queues in the RDMA transport has been added. It is enabled by default for any device that supports it.

The size of a shared receive queue is defined by transport configuration file parameter MaxSRQDepth and nvmf_create_transport RPC method parameter max_srq_depth. Default size is 4096.

Add model number as parameter to construct_nvmf_subsystem (-d option), rather than using hardcoded define.

DIF passthrough feature has been added. DIF setting of the allocated bdevs is exposed to the NVMe-oF initiator and data with DIF from the NVMe-oF initiator is passed through to the allocated bdevs.


The phys_addr parameter in spdk_malloc() and spdk_zmalloc() has been deprecated. For retrieving physical addresses, spdk_vtophys() should be used instead.

spdk_realloc() has been added to reallocate DMA/shared memory.

spdk_pci_device_is_removed() has been added to let the upper-layer SPDK drivers know that device has a pending external hotremove request.

spdk_env_fini() and spdk_env_dpdk_post_fini() were added to release any resources allocated by spdk_env_init() or spdk_env_dpdk_post_init() respectively. It is expected that common usage of those functions is to call them just before terminating the process.

Added spdk_iommu_is_enabled() to report if SPDK application is using IOMMU for DMA.


Dropped support for DPDK 17.07 and earlier, which SPDK won't even compile with right now.

Updated DPDK submodule to DPDK 19.02.


New get_spdk_version RPC method is introduced to get version info of the running SPDK application.

The start_nbd_disk RPC method now take nbd_device as an optional parameter. If nbd_device is specified, use that specified nbd device. If it's not specified, pick available one.

iSCSI target

DIF strip and insert is now supported. DIF settings are not exposed to the iSCSI initiator. DIF is attached into data for write I/O and stripped from data for read I/O.


Added experimental support for running with the external, upstream rte_vhost library. This can be enabled by configuring SPDK with an --without-internal-vhost-lib flag. The minimum supported rte_vhost version (DPDK version) is 19.05-rc1.

As a result of fuzz testing, a lot of data races in vhost-scsi LUN hotplug path were identified and fixed. Those data races could have potentially resulted in SPDK crashes, RPC hangs, or memory leaks if Vhost-SCSI LUN hotplug RPCs were executed while connected VMs were in the middle of restarting.

The SCSI target id in add_vhost_scsi_lun RPC is now optional. If -1 is passed, the first unoccupied target id will be used.


AIO bdev module can now reap I/O completions directly from userspace, significantly improving the overall performance.


Synchronous IO operations no longer use spdk_io_channel, but instead use spdk_fs_thread_ctx. The behavior is otherwise identical.


Added support for caching multiple bdevs using a single bdev as a cache.


Added the notify library that provides a high performance local event bus between libraries. Example usage was added to bdev module, which reports notifications for added and removed bdevs via RPC.


Added new API spdk_sock_readv() to the sock library for performing vectored reads.


The function spdk_subsystem_init() no longer requires spdk_event as an argument.

Changed API of spdk_subsystem_config_json() to no longer be asynchronous.


A bdev module that issues I/O to kernel block devices using the new io_uring Linux kernel API was added. This module requires liburing.


Options to easily compile with profile guided optimization have been added to configure. To use profile guided optimization with SPDK, run ./configure --with-pgo-capture, build SPDK, then run a workload of your choosing. Then, simply run ./configure --with-pgo-enable and recompile to build using the generated profile data. Profile guided optimization can yield very large performance improvements, especially on GCC 8 and clang 7. This may be combined with link time optimization which has been available under the --enable-lto configure option for several releases.

compression bdev/reduce library

Added "reduce" block compression scheme based on using SSDs for storing compressed blocks of storage and presistent memory for metadata. Please see compression for more details.


ocf bdev

New virtual bdev module based on Open CAS Framework has been added. This module allows for the use of one bdev to act as a high performance cache in front of another bdev. Please see documentation for more details. Only write through mode is currently supported and this feature is considered experimental.

event framework

For spdk_app_parse_args, add return value to the callback which parses application specific command line parameters to protect SPDK applications from crashing by invalid values from user input.

By default, all SPDK applications will now reserve all hugepages at runtime. The pre-reserved memory size can be still set with -s or --mem-size option, although the default value was reduced down to 0.

A custom hugetlbfs directory can now be specified via spdk_app_opts. This can be used to configure hugepages with different sizes, a different size limit, or different access permissions than the system's default hugepage pool. SPDK applications can specify a custom hugetlbfs mount with the --huge-dir option.


spdk_vtophys() has been refactored to accept length of the translated region as a new parameter. The function will now update that parameter with the largest possible value for which the memory is contiguous in the physical memory address space.

The following functions were removed:

  • spdk_pci_nvme_device_attach()
  • spdk_pci_nvme_enumerate()
  • spdk_pci_ioat_device_attach()
  • spdk_pci_ioat_enumerate()
  • spdk_pci_virtio_device_attach()
  • spdk_pci_virtio_enumerate()

They were replaced with generic spdk_pci_device_attach() and spdk_pci_enumerate() which require a new spdk_pci_driver object to be provided. It can be one of the following:

spdk_pci_hook_device() and spdk_pci_unhook_device() were added. Those allow adding a virtual spdk_pci_device into the SPDK PCI subsystem. A virtual device calls provided callbacks for each BAR mapping request or PCI config access. It's attachable with spdk_pci_device_attach() or spdk_pci_enumerate() like any other device.

A new spdk_pause() function was added to pause CPU execution for an implementation specific amount of time. Quoting from DPDK function this is based on: "This call is intended for tight loops which poll a shared resource or wait for an event. A short pause within the loop may reduce the power consumption."

A new public header file env_dpdk.h has been introduced, and function spdk_env_dpdk_post_init is added into it. If user is using DPDK, and already called rte_eal_init, then include include/spdk/env_dpdk.h, and call spdk_env_dpdk_post_init() instead of spdk_env_init.

ISA-L has been added as an SPDK submodule. ISA-L is enabled by default on x86 architecture to accelerate algorithms such as CRC for iSCSI and NVMe-oF. Users may still disable ISA-L by explicitly passing –without-isal to the configure script.


A new uuid API spdk_uuid_copy was added to make a copy of the source uuid.

An new parameter init_crc representing the initial CRC value was added to spdk_crc16_t10dif. The parameter can be used to calculate a CRC value spanning multiple separate buffers.

New DIF APIs were added to generate and verify DIF by byte granularity for both DIF and DIX formats. Among them, DIF with copy APIs will be usable to emulate DIF operations such as DIF insert and strip.

Added spdk_strtol and spdk_strtoll to provide additional error checking around strtol and strtoll.

Added spdk_sprintf_append_realloc and spdk_vsprintf_append_realloc for appending a string with automatic buffer re-allocation.


Wrapper functions spdk_nvme_ctrlr_security_send() and spdk_nvme_ctrlr_security_receive() are introduced to support further security protocol development.

admin_timeout_ms was added to NVMe controller initialization options, users can change the default value when probing a controller.

Add two new fields "header_digest" and "data_digest" in struct spdk_nvme_ctrlr_opts, it will be used to enable the digest support for the NVMe/TCP transport.

Add a new TCP/IP transport(located in lib/nvme/nvme_tcp.c) in nvme driver. With this new transport, it can be used to connect the NVMe-oF target with the same TCP/IP support.

Added API, spdk_nvme_ctrlr_is_discovery(), to indicate whether the ctrlr arg refers to a Discovery Controller or not.

Added an API function spdk_nvme_host_id_parse and corresponding object spdk_nvme_host_id for parsing host address and host service ID arguments on a per connection basis.

The RPC construct_nvme_bdev now allows a user to specify a source address and service id for the host to use when connecting to the controller backing the NVMe bdev.

NVMe-oF Target

The spdk_nvmf_tgt_opts struct has been deprecated in favor of spdk_nvmf_transport_opts. Users will no longer be able to specify target wide I/O parameters. spdk_nvmf_tgt_listen will also no longer implicitly initialize a transport with the default target options (since there are none). Instead, a user must manually instantiate the transport with spdk_nvmf_transport_create prior to calling spdk_nvmf_tgt_listen.

Related to the previous change, the rpc set_nvmf_target_options has been renamed to set_nvmf_target_max_subsystems to indicate that this is the only target option available for the user to edit.

Added fields num_shared_buffers and buf_cache_size in struct spdk_nvmf_transport_opts, and also updated the related rpc function nvmf_create_transport, to make this configurable parameter available to users. The num_shared_buffers is used to configure the shared buffer numbers of the transport used by RDMA or TCP transport. buf_cache_size configures number of shared buffers to cache per poll group.


Add a new TCP/IP transport (located in lib/nvmf/tcp.c). With this tranport, the SPDK NVMe-oF target can have a new transport, and can serve the NVMe-oF protocol via TCP/IP from the host.

Added optional mechanism to modify the RDMA transport's behavior when creating protection domains and registering memory. By default, the RDMA transport will use the ibverbs library to create protection domains and register memory. Using spdk_nvme_rdma_init_hooks will subvert that and use an existing registration.


Added enable_bdev_histogram and get_bdev_histogram RPC commands to allow gathering latency data for specified bdev. Please see documentation for more details.

Added required_alignment field to spdk_bdev, that specifies an alignment requirement for data buffers associated with an spdk_bdev_io. Bdev layer will automatically double buffer any spdk_bdev_io that violates this alignment, before the spdk_bdev_io is submitted to the bdev module.

On shutdown, bdev unregister now proceeds in top-down fashion, with claimed bdevs skipped (these will be unregistered later, when virtual bdev built on top of the respective base bdev unclaims it). This allows virtual bdevs to be shut down cleanly as opposed to the previous behavior that didn't differentiate between hotremove and planned shutdown.

The delete_bdev RPC is now deprecated. Users should instead use the specific deletion RPC for the bdev type to be removed (i.e. delete_malloc_bdev).

Added support for separate bandwidth rate limits for read and write to QoS in bdev layer.

Bdev I/O statistics now track unmap opertations.

logical volumes

Logical volume bdev can now be marked as read only using set_read_only_lvol_bdev RPC. This allows for basing clones on top of lvol_bdev without first creating a snapshot.

Added option to change method for data erasure when deleting lvol or resizing down. Default of unmapping clusters can now be changed to writing zeroes or no operation.

Added option to change method for erasing data region on lvol store creation. Default of unmapping can now be changed to writing zeroes or no operation.


"trace flags" are now referred to as "log flags" in the SPDK log API. The set_trace_flag, clear_trace_flag and get_trace_flags RPCs are now deprecated, and set_log_flag, clear_log_flag and get_log_flags RPCs have been added.


New trace_record application was added. It can be used to poll spdk trace shm file and append any new trace entries into another specified file. This can help retain those entries that would otherwise be overwritten in the shm file. See Capturing sufficient trace events for more details.

Number of trace entries in circular buffer per lcore can now be assigned by starting SPDK app with argument "--num-trace-entries <NUM>" provided.

New get_tpoint_group_mask RPC was added to get current tpoint_group_mask, and each tpoint group status. New enable_tpoint_group and disable_tpoint_group RPC were added to enable or disable a specific tpoint group.


EXPERIMENTAL: Added basic flash translation layer module allowing for using Open Channel SSDs as block devices. The module is split into the library (located in lib/ftl) and bdev_ftl (lib/bdev/ftl). See the documentation for more details.


A security vulnerability has been identified and fixed in the SPDK vhost target. A malicious vhost client (i.e. virtual machine) could carefully construct a circular descriptor chain which would result in a partial denial of service in the SPDK vhost target. These types of descriptor chains are now properly detected by the vhost target. All SPDK vhost users serving untrusted vhost clients are strongly recommended to upgrade. (Reported by Dima Stepanov and Evgeny Yakovlev.)

Vhost SCSI and Vhost Block devices can now accept multiple connections on the same socket file. Each connection (internally called a vhost session) will have access to the same storage, but will use different virtqueues, different features and possibly different memory.

vhost scsi

SCSI target hotremove can now be performed even without the VIRTIO_SCSI_F_HOTPLUG feature negotiated. Regardless of VIRTIO_SCSI_F_HOTPLUG support, the hotremoval will be still reported through SCSI sense codes.


DPDK submodule was updated to DPDK 18.11. Note that SPDK does not fully leverage the new multi-process device hotplug yet and continues to work the same way it always did.

Dropped support for DPDK 16.07 and earlier, which SPDK won't even compile with right now.


The following RPC commands deprecated in the previous release are now removed:

  • construct_virtio_user_scsi_bdev
  • construct_virtio_pci_scsi_bdev
  • construct_virtio_user_blk_bdev
  • construct_virtio_pci_blk_bdev
  • remove_virtio_scsi_bdev
  • construct_nvmf_subsystem


The configure options --with-raid and --without-raid that were deprecated in the previous release are now removed.


Starting nbd using spdk_nbd_start is now performed asynchronously.

net framework

Net framework initialization and finish is now done asynchronously.


Added spdk_rpc_is_method_allowed function for checking whether method is permitted in a given state. Added spdk_rpc_get_state to check current state of RPC server. RPC wait_subsystem_init has been added to allow clients to block untill all subsystems are initialized.

json rpc

JSON RPC client is now running in non-blocking mode. Requests are sent and received during spdk_jsonrpc_client_poll. JSON RPC server can now recieve a callback on connection termination or server shutdown using spdk_jsonrpc_conn_add_close_cb and spdk_jsonrpc_conn_del_close_cb.



spdk_nvme_ctrlr_cmd_security_send() and spdk_nvme_ctrlr_cmd_security_receive() were added to support sending or receiving security protocol data to or from nvme controller.

spdk_nvme_ns_get_extended_sector_size() was added. This function includes the metadata size per sector (if any). spdk_nvme_ns_get_sector_size() still returns only the data size per sector, not including metadata.

New send_nvme_cmd RPC was added to allow sending NVMe commands directly to NVMe controller. See the send_nvme_cmd documentation for more details.

Build System

New configure options, --with-shared and --without-shared [default], provide the capability to build, or not, SPDK shared libraries. This includes the single SPDK shared lib encompassing all of the SPDK static libs as well as individual SPDK shared libs corresponding to each of the SPDK static ones. Although the production of the shared libs conforms with conventional version naming practices, such naming does not at this time confer any SPDK ABI compatibility claims.


spdk_bdev_alias_del_all() was added to delete all alias from block device.

A new virtual bdev module has been added to perform at rest data encryption using the DPDK CryptoDev Framework. The module initially uses a software AESNI CBC cipher with experimental support for the Intel QAT hardware accelerator also currently implemented with support for CBC cipher. Future work may include additional ciphers as well as consideration for authentication.

The RAID virtual bdev module is now always enabled by default. The configure –with-raid and –without-raid options are now ignored and deprecated and will be removed in the next release.

Enforcement of bandwidth limits for quality of service (QoS) has been added to the bdev layer. See the new set_bdev_qos_limit documentation for more details. The previous set_bdev_qos_limit_iops RPC method introduced at 18.04 release has been deprecated. The new set_bdev_qos_limit RPC method can support both bandwidth and IOPS limits.

spdk_bdev_config_json() and corresponding get_bdevs_config RPC was removed.

Environment Abstraction Layer and Event Framework

The size parameter of spdk_mem_map_translate is now a pointer. This allows the function to report back the actual size of the translation relative to the original request made by the user.

A new structure spdk_mem_map_ops has been introduced to hold memory map related callbacks. This structure is now passed as the second argument of spdk_mem_map_alloc in lieu of the notify callback.

DPDK 18.08

The DPDK submodule has been updated to the DPDK 18.08 release. SPDK will now automatically utilize DPDK's dynamic memory management with DPDK versions >= 18.05.1.

Hugepages can be still reserved with [-s|--mem-size <size>] option at application startup, but once we use them all up, instead of failing user allocations with -ENOMEM, we'll try to dynamically reserve even more. This allows starting SPDK with --mem-size 0 and using only as many hugepages as it is really needed.

Due to this change, the memory buffers returned by spdk_*malloc() are no longer guaranteed to be physically contiguous.


I/OAT driver can now reinitialize I/OAT channels after encountering DMA errors.

iscsi target

Parameter names of set_iscsi_options and get_iscsi_global_params RPC method for CHAP authentication in discovery sessions have been changed to align with construct_target_node RPC method. Old names are still usable but will be removed in future release.

set_iscsi_discovery_auth and set_iscsi_target_node_auth RPC methods have been added to set CHAP authentication for discovery sessions and existing target nodes, respectively.

The SPDK iSCSI target supports an AuthFile which can be used to load CHAP shared secrets when the iSCSI target starts. SPDK previously provided a default location for this file (/usr/local/etc/spdk/auth.conf) if none was specified. This default has been removed. Users must now explicitly specify the location of this file to load CHAP shared secrets from a file, or use the related iSCSI RPC methods to add them at runtime.

iscsi initiator

The SPDK iSCSI initiator is no longer considered experimental and becomes a first-class citizen among bdev modules. The basic usage has been briefly described in the bdev user guide: iSCSI bdev


The SPDK application framework can now parse long name command line parameters. Most single-character parameters have a long name equivalent now. See the Command Line Parameters documentation for details or use the --help command line parameter to list all available params.

bdevperf -s param (io size) was renamed to -o as -s had been already used by existing apps for memory size.

bdevio can now accept all SPDK command line parameters. The config now has to be provided with -c or --config param.

The following ioat/perf and nvme/perf parameters were renamed as well: -s (io size) to -o -d (mem size) to -s

The ReactorMask config file parameter has been deprecated. Users should use the -m or –cpumask command line option to specify the CPU core mask for the application.

Default config file pathnames have been removed from iscsi_tgt, nvmf_tgt and vhost. Config file pathnames may now only be specified using the -c command line option.

Users may no longer set DPDK_DIR in their environment to specify the location of the DPDK installation used to build SPDK. Using DPDK_DIR has not been the documented nor recommended way to specify the DPDK location for several releases, but removing it ensures no unexpected surprises for users who may have DPDK_DIR defined for other reasons. Users should just use the "configure" script to specify the DPDK location before building SPDK.

Although we know that many developers still use Python 2 we are officially switching to Python3 with requirement that all new code must be valid also for Python 2 up to the EOL which is year 2020.

Invoking interpreter explicitly is forbidden for executable scripts. There is no need to use syntax like "python ./scripts/". All executable scripts must contain proper shebang pointing to the right interpreter. Scripts without shebang musn't be executable.

A Python script has been added to enable conversion of old INI config file to new JSON-RPC config file format. This script can be found at scripts/ Example how this script can be used:

cat old_format.ini | scripts/ > new_json_format.json


Two additional parameters were added to spdk_sock_get_addr() for the server port and client port. These parameters are named "sport" and "cport" respectively.


The following RPC commands have been deprecated:

  • construct_virtio_user_scsi_bdev
  • construct_virtio_pci_scsi_bdev
  • construct_virtio_user_blk_bdev
  • construct_virtio_pci_blk_bdev
  • remove_virtio_scsi_bdev

The construct_virtio_* ones were replaced with a single construct_virtio_dev command that can create any type of Virtio bdev(s). remove_virtio_scsi_bdev was replaced with remove_virtio_bdev that can delete both Virtio Block and SCSI devices.


spdk_file_get_id() returning unique ID for the file was added.


Added jsonrpc-client C library intended for issuing RPC commands from applications.

Added API enabling iteration over JSON object:


Blobstore I/O operations are now based on io_units, instead of blobstore page size. The io_unit size is now the same as the underlying block device's block size. Logical volumes built on a block device with 512B block size can now be used as boot devices in QEMU.


The SPDKCLI interactive command tool for managing SPDK is no longer considered experimental. Support for the iSCSI and NVMe-oF targets has been added.



A new public header file bdev_module.h has been introduced to facilitate the development of new bdev modules. This header includes an interface for the spdk_bdev_part and spdk_bdev_part_base objects to enable the creation of multiple virtual bdevs on top of a single base bdev and should act as the primary API for module authors.

spdk_bdev_get_opts() and spdk_bdev_set_opts() were added to set bdev-wide options.

A mechanism for handling out of memory condition errors (ENOMEM) returned from I/O submission requests at the bdev layer has been added. See spdk_bdev_queue_io_wait().

The spdk_bdev_get_io_stat() function now returns cumulative totals instead of resetting on each call. This allows multiple callers to query I/O statistics without conflicting with each other. Existing users will need to adjust their code to record the previous I/O statistics to calculate the delta between calls.

I/O queue depth tracking and samples options have been added. See spdk_bdev_get_qd(), spdk_bdev_get_qd_sampling_period(), and spdk_bdev_set_qd_sampling_period().

RAID module

A new bdev module called "raid" has been added as experimental module which aggregates underlying NVMe bdevs and exposes a single raid bdev. Please note that vhost will not work with this module because it does not yet have support for multi-element io vectors.


The debug log component flag available on several SPDK applications has been renamed from -t to -L to prevent confusion with tracepoints and to allow the option to be added to tools that already use -t to mean something else.


A new function, spdk_bs_dump(), has been added that dumps all of the contents of a blobstore to a file pointer. This includes the metadata and is very useful for debugging.

Two new operations have been added for thin-provisioned blobs. spdk_bs_inflate_blob() will allocate clusters for all thinly provisioned regions of the blob and populate them with the correct data by reading from the backing blob(s). spdk_bs_blob_decouple_parent() works similarly, but will only allocate clusters that correspond to data in the blob's immediate parent. Clusters allocated to grandparents or that aren't allocated at all will remain thin-provisioned.


Changed the return type of spdk_file_truncate() from void to int to allow the propagation of ENOMEM errors.

NVMe Driver

The new API functions spdk_nvme_qpair_add_cmd_error_injection() and spdk_nvme_qpair_remove_cmd_error_injection() have been added for NVMe error emulation. Users can set a specified command to fail with a particular error status.

Changed the name timeout_sec parameter to timeout_us in spdk_nvme_ctrlr_register_timeout_callback(), and also changed the type from uint32_t to uint64_t. This will give users more fine-grained control over the timeout period.

Basic support for Open Channel SSDs was added. See nvme_ocssd.h

NVMe Over Fabrics

The spdk_nvmf_tgt_destroy() function is now asynchronous and takes a callback as a parameter.

spdk_nvmf_qpair_disconnect() was added to allow the user to disconnect qpairs.

spdk_nvmf_subsystem_get_max_namespaces() was added to query the maximum allowed number of namespaces for a given subsystem.

Build System

The build system now generates a combined shared library ( that may be used in place of the individual static libraries (libspdk_*.a). The combined library includes all components of SPDK and is intended to make linking against SPDK easier. The static libraries are also still provided for users that prefer to link only the minimal set of components required.

git pre-commit and pre-push hooks

The pre-commit hook will run scripts/ and verify there are no formating errors before allowing git commit to run. The pre-push hook runs make CONFIG_WERROR=y with and without CONFIG_DEBUG=y using both the gcc and clang compiler before allowing git push to run. Following each DEBUG build test/unit/ is run and verified. Results are recorded in the make.log file.

To enable type: 'git config core.hooksPath .githooks'. To override after configuration use the git --no-verify flag.


The start_nbd_disk RPC method now returns the path to the kernel NBD device node rather than always returning true.

DPDK 18.05

The DPDK submodule has been rebased on the DPDK 18.05 release. DPDK 18.05 supports dynamic memory allocation, but due to some issues found after the DPDK 18.05 release, that support is not enabled for SPDK 18.07. Therefore, SPDK 18.07 will continue to use the legacy memory allocation model. The plan is to enable dynamic memory allocation after the DPDK 18.08 release which should fix these issues.

Environment Abstraction Layer and Event Framework

The spdk_mem_map_translate() function now takes a size parameter to indicate the size of the memory region. This can be used by environment implementations to validate the requested translation.

The I/O Channel implementation has been moved to its own library - lib/thread. The public API that was previously in spdk/io_channel.h is now in spdk/thread.h The file spdk/io_channel.h remains and includes spdk/thread.h.

spdk_reactor_get_tsc_stats was added to return interesting statistics for each reactor.


IOAT for copy engine is disabled by default. It can be enabled by specifying the Enable option with "Yes" in [Ioat] section of the configuration file. The Disable option is now deprecated and will be removed in a future release.

v18.04: Logical Volume Snapshot/Clone, iSCSI Initiator, Bdev QoS, VPP Userspace TCP/IP


The SPDK vhost-scsi, vhost-blk and vhost-nvme applications have fixes to address the DPDK rte_vhost vulnerability CVE-2018-1059. Please see this security advisory for additional information on the DPDK vulnerability.

Workarounds have been added to ensure vhost compatibility with QEMU 2.12.

EXPERIMENTAL: Support for vhost-nvme has been added to the SPDK vhost target. See the vhost documentation for more details.

Unified Target Application

A new unified SPDK target application, spdk_tgt, has been added. This application combines the functionality of several existing SPDK applications, including the iSCSI target, NVMe-oF target, and vhost target. The new application can be managed through the existing configuration file and JSON-RPC methods.


spdk_mempool_get_bulk() has been added to wrap DPDK rte_mempool_get_bulk().

New memory management functions spdk_malloc(), spdk_zmalloc(), and spdk_free() have been added. These new functions have a flags parameter that allows the user to specify whether the allocated memory needs to be suitable for DMA and whether it should be shared across processes with the same shm_id. The new functions are intended to replace spdk_dma_malloc() and related functions, which will eventually be deprecated and removed.


A new optional bdev module interface function, init_complete, has been added to notify bdev modules when the bdev subsystem initialization is complete. This may be useful for virtual bdevs that require notification that the set of initialization examine() calls is complete.

The bdev layer now allows modules to provide an optional per-bdev UUID, which can be retrieved with the spdk_bdev_get_uuid() function.

Enforcement of IOPS limits for quality of service (QoS) has been added to the bdev layer. See the set_bdev_qos_limit_iops documentation for more details.


The [Rpc] configuration file section, which was deprecated in v18.01, has been removed. Users should switch to the -r command-line parameter instead.

The JSON-RPC server implementation now allows up to 32 megabyte responses, growing as needed; previously, the response was limited to 32 kilobytes.


EXPERIMENTAL: New SPDKCLI interactive command tool for managing SPDK is available. See the SPDKCLI documentation for more details.

NVMe Driver

EXPERIMENTAL: Support for WDS and RDS capable CMBs in NVMe controllers has been added. This support is experimental pending a functional allocator to free and reallocate CMB buffers.

spdk_nvme_ns_get_uuid() has been added to allow retrieval of per-namespace UUIDs when available.

New API functions spdk_nvme_ctrlr_get_first_active_ns() and spdk_nvme_ctrlr_get_next_active_ns() have been added to iterate active namespaces, as well as spdk_nvme_ctrlr_is_active_ns() to check if a namespace ID is active.

NVMe-oF Target

Namespaces may now be assigned unique identifiers via new optional eui64 and nguid parameters to the nvmf_subsystem_add_ns RPC method. Additionally, the NVMe-oF target automatically exposes the backing bdev's UUID as the namespace UUID when available.

spdk_nvmf_subsystem_remove_ns() is now asynchronous and requires a callback to indicate completion.


A number of functions have been renamed:

The old names still exist but are deprecated. They will be removed in the v18.07 release.

spdk_blob_resize() is now an asynchronous operation to enable resizing a blob while I/O are in progress to that blob on other threads. An explicit spdk_blob_sync_md() is still required to sync the updated metadata to disk.

Logical Volumes

A new destroy_lvol_bdev RPC method to delete logical volumes has been added.

Lvols now have their own UUIDs which replace previous LvolStoreUUID_BlobID combination.

New Snapshot and Clone functionalities have been added. User may create Snapshots of existing Lvols and Clones of existing Snapshots. See the lvol snapshots documentation for more details.

Resizing logical volumes is now supported via the resize_lvol_bdev RPC method.


A set of changes were made in the SPDK's lib code altering instances of calls to exit() and abort() to return a failure instead wherever reasonably possible.

spdk_app_start() no longer exit()'s on an internal failure, but instead returns a non-zero error status.

spdk_app_parse_args() no longer exit()'s on help, '-h', or an invalid option, but instead returns SPDK_APP_PARSE_ARGS_HELP and SPDK_APP_PARSE_ARGS_FAIL, respectively, and SPDK_APP_PARSE_ARGS_SUCCESS on success.

spdk_pci_get_device() has been deprecated and will be removed in SPDK v18.07.

I/O Channels

The prototype for spdk_poller_fn() has been modified; it now returns a value indicating whether or not the poller did any work. Existing pollers will need to be updated to return a value.

iSCSI Target

The SPDK iSCSI target now supports the Vector Packet Processing (VPP) framework userspace TCP/IP stack. See the iSCSI VPP documentation for more details.

iSCSI initiator

An iSCSI initiator bdev module has been added to SPDK. This module should be considered experimental pending additional features and tests. More details can be found in lib/bdev/iscsi/README.


The persistent memory (PMDK) bdev module is now enabled using --with-pmdk instead of --with-nvml. This reflects the renaming of the persistent memory library from NVML to PMDK.

Virtio Block driver

A userspace driver for Virtio Block devices has been added. It was built on top of the Virtio library and can be managed similarly to the Virtio SCSI driver. See the Virtio Block reference for more information.

Virtio with 2MB hugepages

The previous 1GB hugepage limitation has now been lifted. A new -g command-line option enables SPDK Virtio to work with 2MB hugepages. See 2MB hugepages for details.

v18.01: Blobstore Thin Provisioning

Build System

The build system now includes a make install rule, including support for the common DESTDIR and prefix variables as used in other build systems. Additionally, the prefix may be set via the configure --prefix option. Example: make install prefix=/usr.


A JSON RPC listener is now enabled by default using a UNIX domain socket at /var/run/spdk.sock. A -r option command line option has been added to enable an alternative UNIX domain socket location, or a TCP port in the format ip_addr:tcp_port (i.e. The Rpc configuration file section is now deprecated and will be removed in the v18.04 release.

I/O Channels

spdk_poller_register() and spdk_poller_unregister() were moved from the event framework (include/spdk/event.h) to the I/O channel library (include/spdk/io_channel.h). This allows code that doesn't depend on the event framework to request registration and unregistration of pollers.

spdk_for_each_channel() now allows asynchronous operations during iteration. Instead of immediately continuing the interation upon returning from the iteration callback, the user must call spdk_for_each_channel_continue() to resume iteration.

Block Device Abstraction Layer (bdev)

The poller abstraction was removed from the bdev layer. There is now a general purpose abstraction for pollers available in include/spdk/io_channel.h


A set of changes were made in the SPDK's lib code altering, instances of calls to exit() and abort() to return a failure instead wherever reasonably possible. This has resulted in return type changes of the API for:

  • spdk_env_init() from type void to int.
  • spdk_mem_map_init() from type void to int.

Applications making use of these APIs should be modified to check for a non-zero return value instead of relying on them to fail without return.

NVMe Driver

SPDK now supports hotplug for vfio-attached devices. But there is one thing keep in mind: Only physical removal events are supported; removing devices via the sysfs remove file will not work.

NVMe-oF Target

Subsystems are no longer tied explicitly to CPU cores. Instead, connections are handed out to the available cores round-robin. The "Core" option in the configuration file has been removed.


A number of functions have been renamed:

The function signature of spdk_blob_close() has changed. It now takes a struct spdk_blob * argument rather than struct spdk_blob **.

The function signature of spdk_bs_iter_next() has changed. It now takes a struct spdk_blob * argument rather than struct spdk_blob **.

Thin provisioning support has been added to the blobstore. It can be enabled by setting the thin_provision flag in struct spdk_blob_opts when calling spdk_bs_create_blob_ext().

NBD device

The NBD application (test/lib/bdev/nbd) has been removed; Same functionality can now be achieved by using the test/app/bdev_svc application and start_nbd_disk RPC method. See the GPT documentation for more details.

FIO plugin

SPDK fio_plugin now supports FIO 3.3. The support for previous FIO 2.21 has been dropped, although it still remains to work for now. The new FIO contains huge amount of bugfixes and it's recommended to do an update.

Virtio library

Previously a part of the bdev_virtio module, now a separate library. Virtio is now available via spdk_internal/virtio.h file. This is an internal interface to be used when implementing new Virtio backends, namely Virtio-BLK.


The MinConnectionIdleInterval parameter has been removed, and connections are no longer migrated to an epoll/kqueue descriptor on the master core when idle.

v17.10: Logical Volumes

New dependencies

libuuid was added as new dependency for logical volumes.

libnuma is now required unconditionally now that the DPDK submodule has been updated to DPDK 17.08.

Block Device Abstraction Layer (bdev)

An fio plugin was added that can route I/O to the bdev layer. See the plugin documentation for more information.

spdk_bdev_unmap() was modified to take an offset and a length in bytes as arguments instead of requiring the user to provide an array of SCSI unmap descriptors. This limits unmaps to a single contiguous range.

spdk_bdev_write_zeroes() was introduced. It ensures that all specified blocks will be zeroed out. If a block device doesn't natively support a write zeroes command, the bdev layer emulates it using write commands.

New API functions that accept I/O parameters in units of blocks instead of bytes have been added:

The bdev layer now handles temporary out-of-memory I/O failures internally by queueing the I/O to be retried later.

Linux AIO bdev

The AIO bdev now allows the user to override the auto-detected block size.

NVMe driver

The NVMe driver now recognizes the NVMe 1.3 Namespace Optimal I/O Boundary field. NVMe 1.3 devices may report an optimal I/O boundary, which the driver will take into account when splitting I/O requests.

The HotplugEnable option in [Nvme] sections of the configuration file is now "No" by default. It was previously "Yes".

The NVMe library now includes a spdk_nvme_ns_get_ctrlr() function which returns the NVMe Controller associated with a given namespace.

The NVMe library now allows the user to specify a host identifier when attaching to a controller. The host identifier is used as part of the Reservations feature, as well as in the NVMe-oF Connect command. The default host ID is also now a randomly-generated UUID, and the default host NQN uses the host ID to generate a UUID-based NQN.

spdk_nvme_connect() was added to allow the user to connect directly to a single NVMe or NVMe-oF controller.

NVMe-oF Target (nvmf_tgt)

The NVMe-oF target no longer requires any in-capsule data buffers to run, and the feature is now entirely optional. Previously, at least 4 KiB in-capsule data buffers were required.

NVMe-oF subsytems have a new configuration option, AllowAnyHost, to control whether the host NQN whitelist is enforced when accepting new connections. If no Host options have been specified and AllowAnyHost is disabled, the connection will be denied; this is a behavior change from previous releases, which allowed any host NQN to connect if the Host list was empty. AllowAnyHost is disabled by default.

NVMe-oF namespaces may now be assigned arbitrary namespace IDs, and the number of namespaces per subsystem is no longer limited.

The NVMe-oF target now supports the Write Zeroes command.

Environment Abstraction Layer

A new default value, SPDK_MEMPOOL_DEFAULT_CACHE_SIZE, was added to provide additional clarity when constructing spdk_mempools. Previously, -1 could be passed and the library would choose a reasonable default, but this new value makes it explicit that the default is being used.


The blobstore super block now contains a bstype field to identify the type of the blobstore. Existing code should be updated to fill out bstype when calling spdk_bs_init() and spdk_bs_load().

spdk_bs_destroy() was added to allow destroying blobstore on device with an initialized blobstore.

spdk_bs_io_readv_blob() and spdk_bs_io_writev_blob() were added to enable scattered payloads.

A CLI tool for blobstore has been added, allowing basic operations through either command line or shell interface. See the blobcli documentation for more details.

Event Framework

The ability to set a thread name, previously only used by the reactor code, is now part of the spdk_thread_allocate() API. Users may specify a thread name which will show up in tools like gdb.


The spdk_trace_dump() function now takes a new parameter to allow the caller to specify an output file handle (stdout or stderr, for example).

Logical Volumes

Logical volumes library built on top of SPDK blobstore has been added. It is possible to create logical volumes on top of other devices using RPC.

See the logical volumes documentation for more information.

Persistent Memory

A new persistent memory bdev type has been added. The persistent memory block device is built on top of libpmemblk. It is possible to create pmem devices on top of pmem pool files using RPC.

See the Pmem Block Device documentation for more information.

Virtio SCSI driver

A userspace driver for Virtio SCSI devices has been added. The driver is capable of creating block devices on top of LUNs exposed by another SPDK vhost-scsi application.

See the Virtio SCSI documentation and Getting Started guide for more information.

Vhost target

The vhost target application now supports live migration between QEMU instances.

v17.07: Build system improvements, userspace vhost-blk target, and GPT bdev

Build System

A configure script has been added to simplify the build configuration process. The existing CONFIG file and make CONFIG_... options are also still supported. Run ./configure --help for information about available configuration options.

A DPDK submodule has been added to make building SPDK easier. If no --with-dpdk option is specified to configure, the SPDK build system will automatically build a known-good configuration of DPDK with the minimal options enabled. See the Building section of for more information.

A Vagrant setup has been added to make it easier to develop and use SPDK on systems without suitable NVMe hardware. See the Vagrant section of for more information.

Userspace vhost-blk target

The vhost library and example app have been updated to support the vhost-blk protocol in addition to the existing vhost-scsi protocol. See the vhost documentation for more details.

Block device abstraction layer (bdev)

A GPT virtual block device has been added, which automatically exposes GPT partitions with a special SPDK-specific partition type as bdevs. See the GPT bdev documentation for more information.

NVMe driver

The NVMe driver has been updated to support recent Intel SSDs, including the Intel® Optane™ SSD DC P4800X series.

A workaround has been added for devices that failed to recognize register writes during controller reset.

The NVMe driver now allocates request tracking objects on a per-queue basis. The number of requests allowed on an I/O queue may be set during spdk_nvme_probe() by modifying io_queue_requests in the opts structure.

The SPDK NVMe fio_plugin has been updated to support multiple threads (numjobs).

spdk_nvme_ctrlr_alloc_io_qpair() has been modified to allow the user to override controller-level options for each individual I/O queue pair. Existing callers with qprio == 0 can be updated to:

... = spdk_nvme_ctrlr_alloc_io_qpair(ctrlr, NULL, 0);

Callers that need to specify a non-default qprio should be updated to:

struct spdk_nvme_io_qpair_opts opts;
spdk_nvme_ctrlr_get_default_io_qpair_opts(ctrlr, &opts, sizeof(opts));
opts.qprio = SPDK_NVME_QPRIO_...;
... = spdk_nvme_ctrlr_alloc_io_qpair(ctrlr, &opts, sizeof(opts));

Environment Abstraction Layer

The environment abstraction layer has been updated to include several new functions in order to wrap additional DPDK functionality. See include/spdk/env.h for the current set of functions.

SPDK Performance Analysis with Intel® VTune™ Amplifier

Support for SPDK performance analysis has been added to Intel® VTune™ Amplifier 2018.

This analysis provides:

  • I/O performance monitoring (calculating standard I/O metrics like IOPS, throughput, etc.)
  • Tuning insights on the interplay of I/O and compute devices by estimating how many cores would be reasonable to provide for SPDK to keep up with a current storage workload.

See the VTune Amplifier documentation for more information.

v17.03: Blobstore and userspace vhost-scsi target

Blobstore and BlobFS

The blobstore is a persistent, power-fail safe block allocator designed to be used as the local storage system backing a higher-level storage service. See the blobstore documentation for more details.

BlobFS adds basic filesystem functionality like filenames on top of the blobstore. This release also includes a RocksDB Env implementation using BlobFS in place of the kernel filesystem. See the BlobFS documentation for more details.

Userspace vhost-scsi target

A userspace implementation of the QEMU vhost-scsi protocol has been added. The vhost target is capable of exporting SPDK bdevs to QEMU-based VMs as virtio devices. See the vhost documentation for more details.

Event framework

The overhead of the main reactor event loop was reduced by optimizing the number of calls to spdk_get_ticks() per iteration.

NVMe library

The NVMe library will now automatically split readv/writev requests with scatter-gather lists that do not map to valid PRP lists when the NVMe controller does not natively support SGLs.

The identify and perf NVMe examples were modified to add a consistent format for specifying remote NVMe over Fabrics devices via the -r option. This is implemented using the new spdk_nvme_transport_id_parse() function.

iSCSI Target

The [Nvme] section of the configuration file was modified to remove the BDF directive and replace it with a TransportID directive. Both local (PCIe) and remote (NVMe-oF) devices can now be specified as the backing block device. A script to generate an entire [Nvme] section based on the local NVMe devices attached was added at scripts/

NVMe-oF Target

The [Nvme] section of the configuration file was modified to remove the BDF directive and replace it with a TransportID directive. Both local (PCIe) and remote (NVMe-oF) devices can now be specified as the backing block device. A script to generate an entire [Nvme] section based on the local NVMe devices attached was added at scripts/

v16.12: NVMe over Fabrics host, hotplug, and multi-process

NVMe library

The NVMe library has been changed to create its own request memory pool rather than requiring the user to initialize the global request_mempool variable. Apps can be updated by simply removing the initialization of request_mempool. Since the NVMe library user no longer needs to know the size of the internal NVMe request structure to create the pool, the spdk_nvme_request_size() function was also removed.

The spdk_nvme_ns_cmd_deallocate() function was renamed and extended to become spdk_nvme_ns_cmd_dataset_management(), which allows access to all of the NVMe Dataset Management command's parameters. Existing callers can be updated to use spdk_nvme_ns_cmd_dataset_management() with SPDK_NVME_DSM_ATTR_DEALLOCATE as the type parameter.

The NVMe library SGL callback prototype has been changed to return virtual addresses rather than physical addresses. Callers of spdk_nvme_ns_cmd_readv() and spdk_nvme_ns_cmd_writev() must update their next_sge_fn callbacks to match.

The NVMe library now supports NVMe over Fabrics devices in addition to the existing support for local PCIe-attached NVMe devices. For an example of how to enable NVMe over Fabrics support in an application, see examples/nvme/identify and examples/nvme/perf.

Hot insert/remove support for NVMe devices has been added. To enable NVMe hotplug support, an application should call the spdk_nvme_probe() function on a regular basis to probe for new devices (reported via the existing probe_cb callback) and removed devices (reported via a new remove_cb callback). Hotplug is currently only supported on Linux with the uio_pci_generic driver, and newly-added NVMe devices must be bound to uio_pci_generic by an external script or tool.

Multiple processes may now coordinate and use a single NVMe device simultaneously using DPDK Multi-process Support.

NVMe over Fabrics target (nvmf_tgt)

The nvmf_tgt configuration file format has been updated significantly to enable new features. See the example configuration file etc/spdk/ for more details on the new and changed options.

The NVMe over Fabrics target now supports virtual mode subsystems, which allow the user to export devices from the SPDK block device abstraction layer as NVMe over Fabrics subsystems. Direct mode (raw NVMe device access) is also still supported, and a single nvmf_tgt may export both types of subsystems simultaneously.

Block device abstraction layer (bdev)

The bdev layer now supports scatter/gather read and write I/O APIs, and the NVMe blockdev driver has been updated to support scatter/gather. Apps can use the new scatter/gather support via the spdk_bdev_readv() and spdk_bdev_writev() functions.

The bdev status returned from each I/O has been extended to pass through NVMe or SCSI status codes directly in cases where the underlying device can provide a more specific status code.

A Ceph RBD (RADOS Block Device) blockdev driver has been added. This allows the iscsi_tgt and nvmf_tgt apps to export Ceph RBD volumes as iSCSI LUNs or NVMe namespaces.

General changes

libpciaccess has been removed as a dependency and DPDK PCI enumeration is used instead. Prior to DPDK 16.07 enumeration by class code was not supported, so for earlier DPDK versions, only Intel SSD DC P3x00 devices will be discovered by the NVMe library.

The env environment abstraction library has been introduced, and a default DPDK-based implementation is provided as part of SPDK. The goal of the env layer is to enable use of alternate user-mode memory allocation and PCI access libraries. See doc/ for more details.

The build process has been modified to produce all of the library files in the build/lib directory. This is intended to simplify the use of SPDK from external projects, which can now link to SPDK libraries by adding the build/lib directory to the library path via -L and linking the SPDK libraries by name (for example, -lspdk_nvme -lspdk_log -lspdk_util).

nvmf_tgt and iscsi_tgt now have a JSON-RPC interface, which allows the user to query and modify the configuration at runtime. The RPC service is disabled by default, since it currently does not provide any authentication or security mechanisms; it should only be enabled on systems with controlled user access behind a firewall. An example RPC client implemented in Python is provided in scripts/

v16.08: iSCSI target, NVMe over Fabrics maturity

This release adds a userspace iSCSI target. The iSCSI target is capable of exporting NVMe devices over a network using the iSCSI protocol. The application is located in app/iscsi_tgt and a documented configuration file can be found at etc/spdk/

This release also significantly improves the existing NVMe over Fabrics target.

  • The configuration file format was changed, which will require updates to any existing nvmf.conf files (see etc/spdk/
    • SubsystemGroup was renamed to Subsystem.
    • AuthFile was removed (it was unimplemented).
    • nvmf_tgt was updated to correctly recognize NQN (NVMe Qualified Names) when naming subsystems. The default node name was changed to reflect this; it is now "".
    • Port and Host sections were merged into the Subsystem section
    • Global options to control max queue depth, number of queues, max I/O size, and max in-capsule data size were added.
    • The Nvme section was removed. Now a list of devices is specified by bus/device/function directly in the Subsystem section.
    • Subsystems now have a Mode, which can be Direct or Virtual. This is an attempt to future-proof the interface, so the only mode supported by this release is "Direct".
  • Many bug fixes and cleanups were applied to the nvmf_tgt app and library.
  • The target now supports discovery.

This release also adds one new feature and provides some better examples and tools for the NVMe driver.

  • The Weighted Round Robin arbitration method is now supported. This allows the user to specify different priorities on a per-I/O-queue basis. To enable WRR, set the arb_mechanism field during spdk_nvme_probe().
  • A simplified "Hello World" example was added to show the proper way to use the NVMe library API; see examples/nvme/hello_world/hello_world.c.
  • A test for measuring software overhead was added. See test/lib/nvme/overhead.

v16.06: NVMf userspace target

This release adds a userspace NVMf (NVMe over Fabrics) target, conforming to the newly-released NVMf 1.0/NVMe 1.2.1 specification. The NVMf target exports NVMe devices from a host machine over the network via RDMA. Currently, the target is limited to directly exporting physical NVMe devices, and the discovery subsystem is not supported.

This release includes a general API cleanup, including renaming all declarations in public headers to include a spdk prefix to prevent namespace clashes with user code.

  • NVMe
    • The nvme_attach() API was reworked into a new probe/attach model, which moves device detection into the NVMe library. The new API also allows parallel initialization of NVMe controllers, providing a major reduction in startup time when using multiple controllers.
    • I/O queue allocation was changed to be explicit in the API. Each function that generates I/O requests now takes a queue pair (spdk_nvme_qpair *) argument, and I/O queues may be allocated using spdk_nvme_ctrlr_alloc_io_qpair(). This allows more flexible assignment of queue pairs than the previous model, which only allowed a single queue per thread and limited the total number of I/O queues to the lowest number supported on any attached controller.
    • Added support for the Write Zeroes command.
    • examples/nvme/perf can now report I/O command latency from the the controller's viewpoint using the Intel vendor-specific read/write latency log page.
    • Added namespace reservation command support, which can be used to coordinate sharing of a namespace between multiple hosts.
    • Added hardware SGL support, which enables use of scattered buffers that don't conform to the PRP list alignment and length requirements on supported NVMe controllers.
    • Added end-to-end data protection support, including the ability to write and read metadata in extended LBA (metadata appended to each block of data in the buffer) and separate metadata buffer modes. See spdk_nvme_ns_cmd_write_with_md() and spdk_nvme_ns_cmd_read_with_md() for details.
  • IOAT
    • The DMA block fill feature is now exposed via the ioat_submit_fill() function. This is functionally similar to memset(), except the memory is filled with an 8-byte repeating pattern instead of a single byte like memset.
  • PCI
    • Added support for using DPDK for PCI device mapping in addition to the existing libpciaccess option. Using the DPDK PCI support also allows use of the Linux VFIO driver model, which means that SPDK userspace drivers will work with the IOMMU enabled. Additionally, SPDK applications may be run as an unprivileged user with access restricted to a specific set of PCIe devices.
    • The PCI library API was made more generic to abstract away differences between the underlying PCI access implementations.

v1.2.0: IOAT user-space driver

This release adds a user-space driver with support for the Intel I/O Acceleration Technology (I/OAT, also known as "Crystal Beach") DMA offload engine.

  • IOAT
    • New user-space driver supporting DMA memory copy offload
    • Example programs ioat/perf and ioat/verify
    • Kernel-mode DMA engine test driver kperf for performance comparison
  • NVMe
    • Per-I/O flags for Force Unit Access (FUA) and Limited Retry
    • Public API for retrieving log pages
    • Reservation register/acquire/release/report command support
    • Scattered payload support - an alternate API to provide I/O buffers via a sequence of callbacks
    • Declarations and nvme/identify support for Intel SSD DC P3700 series vendor-specific log pages and features
  • Updated to support DPDK 2.2.0

v1.0.0: NVMe user-space driver

This is the initial open source release of the Storage Performance Development Kit (SPDK).


  • NVMe user-space driver
  • NVMe example programs
    • examples/nvme/perf tests performance (IOPS) using the NVMe user-space driver
    • examples/nvme/identify displays NVMe controller information in a human-readable format
  • Linux and FreeBSD support