Based on the IBM descriptions, this first generation enterprise SSHD is based on Seagate’s 2.5-inch 600GB drive platform, spinning at 10K RPM with a 6Gb/s SAS interface. Though it is not identified in the description, the drive features 16GB of NAND flash and 128MB of cache on-board. Designed for mid-range servers and storage subsystems, Seagate’s enterprise SSHD utilizes intelligent algorithms to deliver solid-state like performance to the most heavily accessed data. Seagate is targeting performance at a 100% I/O improvement over the base 10K drive.
How does it work? Seagate utilizes the 600GB of magnetic media for storage of all data written, while also storing a primary copy of all cached data. 128MB of DRAM is used to buffer all reads and cache all writes. While 16GB of eMLC NAND serves as a read cache for all active data, and a non-volatile cache (NVC) for writes cached in DRAM. The obvious result is much improved random read performance, and with NVC enabled, much faster write response times.
The not so obvious benefit: the hard disk drive (HDD) backend improves NAND reliability & lifespan, because a copy of the data is available on disk even if an error occurs reading the NAND. In cases of high write activity, the drive can avoid the NAND altogether. We all know NAND endurance is a function of temperature, write activity & retention, and since the NAND data is refreshed periodically, we limit how long data lives in NAND yielding much higher write counts.
So, this is all great, but how much does it improve system performance?
For the past year, Seagate and IBM have been putting an enterprise SSHD prototype through the ringer. After months of testing in Seagate and IBM labs, the first enterprise SSHD has been shown to greatly improve overall system performance for mission critical applications.
Based on preliminary performance testing using standard system benchmarking tools, the 10,000 RPM enterprise SSHD boasts IOPS over 2X better than the current 300GB 10,000 RPM hard disk drive, and at low latency (< 5ms), the enterprise hybrid drive’s IOPS deliver an over 15X gain. The end result is much improved and cost effective performance for IBM Series x servers running mission critical applications.
The enterprise SSHD Seagate and IBM have been working on is just the beginning. Even faster enterprise SSHDs (available to the channel) will be available later this year…stay tuned.