IBM Adds New SAS, SSD Disks to Servers

Published: March 16, 2009

by Timothy Prickett Morgan

While the main chasses in the Power Systems product lines have had slots for SAS drives since the System i and System p product convergence last April, it looks like the System x and BladeCenter lines are going to get the latest and greatest disk technology first this time around.

Last week, IBM announced new small form factor SAS drives, those with 2.5-inch wide drive cases rather than the earlier 3.5-inch wide cases that were standard for SCSI drives since IBM shipped the first such 3.5-inch drives back when it was still called the AS/400 and when IBM Rochester had the best disk drive research and manufacturing facilities in the world. IBM sold off its disk drive business to Hitachi, of course, and we don't know where the company is sourcing its new 2.5-inch drives, but now there is a 2.5-inch SAS drive with 146 GB of capacity that spins at 15K RPM that can plug into System x rack and tower servers and BladeCenter blade modules. IBM's current line of SAS drives for these server lines came in 73 GB and 146 GB capacities, but spun at a slower 10K RPM. The company already sold a 73 GB 15K RPM 2.5-icn SAS drive as well. The 15K RPM drives have and average latency of 2 millisecond and an average read seek time of 2.9 milliseconds, which is 33.3 percent lower latency and 27.5 percent faster on the seek.

IBM also fattened up its 10K RPM disks for the System x and BladeCenter iron with a 300 GB 10K RPM drive, which has an average latency of 3 milliseconds and an average read seek time of 4 milliseconds. (A millisecond is about the time it takes to blink, so it takes about seven blinks on average to find a bit of data on these drives, which is reduced to just under five blinks with the 15K RPM drives.)

All of these small form factor SAS drives support the latest 6 Gb/sec SAS interface, and they will be available on March 31.

IBM also said last week that its System x and BladeCenter servers as well as its EXP3000 disk arrays will begin selling on the same day a new 50 GB solid state drive (SSD) that is build from flash memory. The unit will come in 2.5-inch and 3.5-inch form factors and will deliver up to 2,600 I/O operations per second (IOPS); a top-end 15K RPM disk can do about 320 IOPs or so going full tilt boogie. I have seen SSDs that plug into SAS or SATA slots that can do 20,000 to 30,000 IOPS, and SSDs that plug directly PCI-Express peripheral slots that push up to 200,000 IOPS. So I am, quite honestly, not impressed by 2,600 IOPS. So IBM better not think it can charge a lot of dough for this flash drive.

No word on pricing for these SAS and SSD units, or when Power Systems boxes will get them. Hopefully soon.

Back in October 2008, IBM announced a 450 GB SAS drive in a 3.5-inch form factor that spun at 10K RPM for the Power Systems lineup; this drive formats down to 428 GB with the i 6.1 operating system.

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