v19.01: (Upcoming Release)


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


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.

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.


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.


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.


"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.



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