Seagate has been hinting about the coming of a Seagate enterprise solid state hybrid drive (SSHD) for the past year. That time has arrived in the form of a storage upgrade in IBM System x servers.
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. 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 heavily accessed data. Seagate is targeting performance at a 100% I/O improvement over the base 10K drive.
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 is the fact that 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. NAND endurance is a function of temperature, write activity & retention, and since the NAND data is refreshed periodically, Seagate limits how long data lives in NAND yielding much higher write counts.
According to tests preformed in Seagate and IBM labs using standard system benchmarking tools, the 10,000 RPM enterprise SSHD boasts IOPS over 2X better than Seagate's current 300GB 10,000 RPM hard disk drive, and at low latency (< 5ms), the enterprise hybrid drive?s IOPS deliver an over 15X gain.
Seagate plans to releae even faster enterprise SSHDs later this year.