First 10,000rpm Hybrid HDD, Fastest Enterprise Rotating Device

We first discovered this new unit following an announcement from IBM that didn’t reveal the name of the manufacturer. But a Seagate’s blog proves that Seagate was the original maker, discreetly confirming the information not published through a press release as usual.

It is the first enterprise hybrid HDD (SSHD or solid state hybrid drive) available in the industry and shipped by IBM since June 19 for selected System x servers. It’s also probably the fastest magnetic hard disk drive never seen.

Until now about all the hybrid drives were 2.5-inch notebook units with SATA interface, the only exception being a desktop 3.5-inch HDD from Seagate launched last March.

Here, for the first time, a flash cache (16GB eMLC, a flash capacity record for HDD) is incorporated in a 6Gb SAS rotating unit as well as 128MB on DRAM. Note that flash is used only as a read cache, not to write data.

More precisely the 600GB of magnetic media stores all data written, while also recording a primary copy of all cached data. 128MB – and not 64MB as usual – of DRAM is used to buffer all reads and cache all writes, while NAND serves as a read cache for hot data using a special algorithm. Furthermore there is a non-volatile cache (8MB NVC) for writes cached in DRAM. The result is improved random read performance, and, with NVC, faster write response times.

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 and retention, and since the NAND data is refreshed periodically, Seagate limits how long data lives in NAND yielding higher write counts.

The HDD maker also said that, based on preliminary performance testing using standard system benchmarking tools, the enterprise hybrid device boasts IO/s over 2x better than the current 300GB 10,000rpm HDD and at less than 5ms latency. The company is targeting performance at a 100% I/O improvement over the base 10,000rpm drive, but with 151MB/s average sustained transfer rate, it’s much slower than a lot of SSDs.

Total capacity is 600GB, rotational speed 10,000rpm and MTBF 2 million hours, z-height being 15mm. Non hybrid Seagate 10,000rpm regular HDD reached more than that, 900GB.

The new drive was "based on the IBM descriptions".

Last sentence on Seagate’s blog: "Even faster enterprise SSHDs (available to the channel) will be available later this year … stay tuned."