Sundry Spring Power Systems Storage Enhancements

May 11, 2009 Timothy Prickett Morgan

Along with the April 28 Power6+ enhancements to the entry and midrange server lineup as well as the addition of solid state disks–finally–to the Power Systems lineup, IBM made a slew of storage announcements relating to the Power Systems lineup. In many ways, the announcements had more to do with storage than they did with processors, but this kind of got buried in the zillions of announcements that Big Blue tried to pack in its second Dynamic Infrastructure blitz.

I touched on some of these storage announcements back in the April 27 issue, based on the information I could cull ahead of the announcements the following day. But this story is based on more detailed feeds and speeds and such that I have been able to get my hands on since announcement day.

Probably the most important new storage product, aside from the SSDs, is the new PCI-X large cache SAS RAID disk controller. Depending on the machine, it comes as feature number 5904, 5906, or 5908, and it has 1.5 GB of write cache and 1.6 GB of read cache memory on the card. This controller supports the 3.5-inch and 2.5-inch SAS drives that can be used inside of Power Systems and in their I/O drawers. These new features are an alternative to the SCSI disk adapter (features 5778, 5780, and 5782) that have the same read and write configuration and that use the same PCI-X peripheral port. IBM has not announced a PCI-Express 1.0 or 2.0 version of either the SCSI or SAS version of this large cache disk controller, and considering that IBM is telling customers that it will withdraw SCSI disks entirely from marketing by the end of 2009 (I have heard this will happen in August), it seems likely that there never will be a PCI-Express version of the SCSI variant of the large cache adapter. But it seems likely that a SAS version will eventually see the light of day, but IBM sources tell me not to expect it in 2009.

On 15K RPM drives, IBM says that SAS drives will deliver better performance than SCSI drives of equivalent capacity, and that they also, in general cost less money to buy and maintain. The controller supports the attachment of up to 60 SAS disk drives or up to 8 SSDs. (SSDs have very high I/O rates, in this case about 100 times that of a SCSI disk drive, so you can’t put that many on the RAID controller or it will choke on all of the I/O requests.)

The SAS large cache RAID adapter supports i 6.1, AIX, and Linux, by the way, while the SCSI version was only available with i5/OS V5R4 and i 6.1. This controller will be available on May 22 on Power 520, 550, 560, 570, and 595 servers using Power6 or Power6+ processors, but customers using earlier Power5 and Power5+ iron will have to wait until July. The new large cache SAS RAID disk controller costs $8,500 on Power 560 and smaller boxes, the same price as for the SCSI version of the controller; on Power 570 and Power 595 machines, it costs $11,250. Either way, the controller eats up two slots in a machine or I/O expansion drawer because it comes with mirrored write caches.

There’s another less cache-heavy disk controller that IBM has announced, feature 5903, the PCI-Express SAS RAID adapter, which has 380 MB of write cache and which obviously plugs into a PCI-Express slot (an x4 slot, in this case). This SAS controller can support 2.5-inch or 3.5-inc SAS drives, and like the larger controller above, it eats two slots because of the mirrored the write caches. This PCI-Express RAID controller currently only supports AIX or Linux, but will support i 6.1 before the end of 2009, according to Big Blue. It costs $2,199 on smaller Power Systems, but costs $2,910 on larger boxes.

IBM also announced a PCI-Express x4 SAS adapter (feature 5901), which is used to control 2.5-inch SAS disks (also known as small form factor or SFF drives) or full-size 3.5-inch SAS drives. This disk drive is functionally similar to the feature 5912 and 5900 PCI-X dual-port adapters. This adapter costs $749.

On the I/O drawer front, IBM has created a new EXP 12S I/O drawer, one that supports 20 Gb/sec double data rate InfiniBand speeds, double that of the prior 12X I/O links that debuted with the converged Power Systems last year. (IBM didn’t want to admit that it was using InfiniBand for channel links between I/O drawers and servers, just like it didn’t want to admit that Remote I/O was really Fibre Channel.) This new 12X DDR I/O drawer comes in standard 19-inch widths (feature 5802) or 24-inch width (feature 5803 and 5873, matching the rack chassis widths of the Power 595 and System z mainframe servers). It supports 139 GB, 282 GB, and 428 GB SAS drives on the i platform, and 146 GB, 300 GB, and 450 GB disks on the AIX and Linux platforms. (The difference in the capacities have nothing to do with the disk drive, but the formatting block sizes of the i and AIX/Linux operating systems.) IBM is warning customers that it might withdraw the 139 GB/146 GB disks later this year, but apparently has not made up its mind yet.

Anyway, the 24-inch version of the EXP 12S drawer comes in a 4U chassis and has 20 PCX-Express slots and 26 drive bays for 2.5-inch SAS drives; it costs $28,500 with no disks in it. The 19-inch version has 10 PCI-Express slots and room for up to 18 of the 2.5-inch SAS drives; it costs $14,426 on Power 570s, and $10,900 on smaller Power Systems with a base number of 2.5-inch SAS disks. (I can’t figure out how many, though.) What I do know is that the Power6 and Power6+ chips have what IBM calls a GX I/O bus controller on them and that the InfiniBand (oops, 12X) I/O ports plug into the system board and talk to this on-chip controller and deliver very fast and integrated I/O bandwidth into the processor complex. And you’d think IBM would brag about this, but nope. I am figuring this out by myself, as usual. No other processor that I am aware of has InfiniBand I/O controllers on the chip. (Sun Microsystems put some PCI-Express and Ethernet ports on some of its Sparc T series chips.)

The Power Systems lineup now has 2.5-inch SAS disks. A 69.7 GB 15K RPM 2.5-inch SAS drive can be used in Power 520 or Power 550 chasses (feature 1884); it costs $498. On AIX or Linux partitions, you have to use feature 1883, which formats to 73.4 GB and which costs the same $498. AIX and Linux shops can also use feature 1882, which is a 146.8 GB 2.5-inch SAS disk that costs $650. These disks are also available in the EXP 12S I/O drawers.

One other big announcement on the storage front. IBM is back-porting the first-generation SAS 3.5-inch disks and EXP 12S I/O drawers (the ones using single data rate InfiniBand) to its System p 520, 550, 560Q, 570, and 595 machines. These are Power5 and Power5+ servers, and customers using these boxes wanted to be able to use relatively newer I/O on these older boxes. IBM did not put the latest small form factor SAS drives and DDR InfiniBand I/O drawers on the older boxes, however. Incidentally, AIX and Linux cannot use SAS drives to boot on Power5 or Power5+ machinery. On these AIX and Linux boxes and their EXP 12S I/O drawers, IBM is supporting feature 3647 (146 GB for $498), feature 3648 (300 GB for $1,150), and feature 3649 (450 GB for $1,599) on entry and midrange Power Systems; but these same disks cost $659, $1,522, and $2,116 on Power 570 and Power 595 machines. IBM is also supporting the PCI-X SAS RAID adapter, feature 5902, on the Power5 and Power5+ iron; it costs $1,889 on small Power Systems and $2,500 on Power 570 and larger machines.

You sensing a trend here? Instead of gouging AS/400 shops to help pump up the profits of RS/6000 sales on the same iron, now IBM is charging more money on Power 570 and Power 595 gear for the exactly same features used on Power 560 and smaller machines. The only different is a feature number in the microcode that won’t let the cheaper peripherals work with the more expensive servers. Grrrrrrrrr. . . .

Finally, IBM has expanded the external disk array support on the Power Systems platform. The Smart Fibre Channel adapter (feature 5749) can now plug into Power5 and Power5+ servers running i 6.1 to attach to the high-end DS8000 disk arrays. Similarly, the feature 5774 and feature 5749 Smart Fibre Channel adapter cards support the midrange DS6800 arrays on Power5, Power5+, Power6, and Power6+ servers running i 6.1. And the DS5100 and DS5300 entry arrays are supported on Power6 and Power6+ servers that talk to disk arrays through the Virtual I/O Server running inside of a PowerVM logical partition, and support flash copy and replication for i 6.1 data and objects. Here’s the current rundown on external disk array support as it stands with the Power Systems i platform:

IBM doesn’t support i 6.1 attachment to the DS5000 servers from Power-based blade servers through VIOS. But as this table shows, that capability is expected in the second half of 2009.

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