Hewlett-Packard, with its partner Seagate, has announced new 300GB capacity serial attached SCSI (SAS)
Hard drives are one of the villains in datacenter power woes, and it’s been a lot harder to reduce the power they need than it has been with CPUs. That’s because drives have to spin as fast as possible, which generates heat and consumes power. At the same time, the volume of data these drives are expected to handle is exploding.
Whether it’s user-generated or business analytics, petabye
Up to now, if you wanted a 300GB SAS-based drive, which spins at 10,000 revolutions per minute (RPM), it had to be a 3.5-inch drive. The 2.5-inch form factor models have had a maximum capacity of 146GB, but the new HP/Seagate drive hits the 300GB barrier.
This means putting twice as many 2.5-inch drives in a 3U drive bay as 3.5-inch drives, doubling capacity, I/O per second (IOPS) and still reducing power, said Jimmy Daley, ISS marketing manager for HP (NYSE: HPQ). The drives are generically referred to as “HP SAS drives” and primarily used in its ProLiant servers.
“Small form factor SAS brings a significant power advantage,” he told InternetNews.com. He estimates that would be around 50 percent, but it could vary based on use. “The motor doesn’t have as much mass to move, the platters are smaller, so the bulk of the power in physically moving the platters around is less.”
Seagate brought its storage expertise to the table while HP brought its knowledge of server and storage integration, backplane design, and power and footprint engineering. The two companies worked on everything from the interface to the trays to minimize vibration.
Daley said the eventual goal is that all enterprise drives, both 10,000 RPM and 15,000 RPM, the fastest drives available, will achieve the smaller 2.5-inch form factor. “The density and reliability lend itself for a natural progression of small form factor adoption,” he said.
In search of the enterprise sweet spot
Krishna Chander, senior analyst for storage at iSuppli, agreed on this point. “When they go a smaller sized drive, power consumption goes down considerably,” he told InternetNews.com. But he said the 10k RPM drive is not the sweet spot of enterprise storage, 15k RPM drives are.
“The demand for 300GB drives in the 10k space has not been too high,” said Chander. “The industry has been delegating 10k for archiving and 15k drives for transaction services. If it was a 300GB 15k drive, I would say it’s a bigger deal.”
Next page: Future developments
Page 2 of 2
Because 10k drives are used for less time sensitive activities like archiving, where instant response is not as vital, he said a 3.5-inch Serial ATA drive, the kind used in regular desktop computers, is often good enough. Those drives spin at 7,200 RPM but are at the 1 terabyte level, so one 1TB SATA drive can often be good enough for performance needs, and certainly cheaper than three 300GB SAS drives.
HP maintains that it can get greater performance with 2.5-inch 10k drives over 3.5-inch 15k drives thanks to numbers. A 2U drive bay can hold 25 2.5-inch drives, whereas a 3U bay can only hold 14 3.5-inch drives. More spindles means more IOPS, said Daley. A 2U bay of 2.5-inch drives has 40 percent higher IOPS than the 3U bay of 3.5-inch 15k drives simply because there are more drives to spin at once, while still consuming 12 percent less power.
Future developments
Daley said HP and Seagate are working on 2.5-inch 15k drives, which currently max out at 72GB capacity. The largest 3.5-inch 15k drive has 450GB of capacity. Because they spin so fast – 250 rotations per second – it’s not that easy to increase capacity, as the drive head can only seek so fast. Still, HP and Seagate expect to release a 146GB 15k drive next year.
Another evolutionary step will be the introduction of high throughput SAS. Currently, SAS maxes out at three gigabits per second of throughput. SATA runs at half that speed. Next year, SAS is expected to double to 6Gbits/sec.
These new 300GB 10k drives will be the basis for that, said Daley. While they won’t be 6Gbits natively, much of what is found in these new drives will be reused in drives that support the 6Gbit interfaces.
