The Storage Performance Development Kit (SPDK) provides a set of tools and libraries for writing high performance, scalable, user-mode storage applications. It achieves high performance through the use of a number of key techniques:

  • Moving all of the necessary drivers into userspace, which avoids syscalls and enables zero-copy access from the application.
  • Polling hardware for completions instead of relying on interrupts, which lowers both total latency and latency variance.
  • Avoiding all locks in the I/O path, instead relying on message passing.

The bedrock of SPDK is a user space, polled-mode, asynchronous, lockless NVMe driver. This provides zero-copy, highly parallel access directly to an SSD from a user space application. The driver is written as a C library with a single public header.

SPDK further provides a full block stack as a user space library that performs many of the same operations as a block stack in an operating system. This includes unifying the interface between disparate storage devices, queueing to handle conditions such as out of memory or I/O hangs, and logical volume management.

Finally, SPDK provides NVMe-oF, iSCSI, and vhost servers built on top of these components that are capable of serving disks over the network or to other processes. The standard Linux kernel initiators for NVMe-oF and iSCSI interoperate with these targets, as well as QEMU with vhost. These servers can be up to an order of magnitude more CPU efficient than other implementations. These targets can be used as examples of how to implement a high performance storage target, or used as the basis for production deployments.

SPDK NVMe-oF TCP Transport

Nov 15, 2018 • Jim Harris

NVM Express has ratified TCP as a new transport for NVMe-oF! The announcement can be found here. Quoting from the NVM Express announcement:

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Hitachi SPDK NVMe-oF Performance Report

Nov 8, 2018 • Shuhei Matsumoto

We have been doing some work to evaluate the performance of SPDK and gain some hands-on experience with the SPDK NVMe-oF Target and Initiator. The Hitachi SPDK NVMe-oF Performance Report contains our test configuration and performance results. In summary, we observed up to 8x more IOPS/Core with SPDK NVMe-oF Target and Initiator, vs the Linux Kernel, and a 90% reduction in the software latency. Many thanks to John Kariuki and the SPDK team.

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New Core Maintainer - Darek Stojaczyk

Nov 7, 2018 • Jim Harris

The SPDK project has a team of core maintainers who are responsible for providing technical oversight for the SPDK project, including final review and merging of patches into the SPDK code base. As the SPDK project continues to grow, the core maintainer team needs to grow as well. With that in mind, I am pleased to announce that we are adding Dariusz (Darek) Stojaczyk to the core maintainer team!

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