IBM Adds New SSD and Fat SFF Disk to Power Systems

September 13, 2010 Timothy Prickett Morgan

Like most of you, I am still chewing through the latest Power Systems announcements from IBM. We covered the five new systems that Big Blue announced on August 17 in as much detail as was possible on announcement day, and followed up with detailed price and performance information in the weeks following the announcement. We’ve also gone into pricing for IBM i on the boxes, and the deals the company is making on software to encourage shops to upgrade to new Power7 iron.

Now is the time to drill down into some important storage announcements that were buried in the August 17 announcements. IBM has a new fat solid state drive (SSD) that we knew was coming because I told you about it back in May when IBM put out benchmarks using the SSD module to push up the performance of the Power 780 on the TPC-C online transaction processing benchmark test.

IBM is pairing up four SAS versions of SandForce enterprise multi-level cell (eMLC) flash drives with a SAS RAID controller (3 Gb/sec) to create a new SSD subsystem that can be plugged into any of the new Power Systems servers. Back in May, I guessed that the controller was a SATA controller because SandForce’s SF-1500 SSD is a SATA drive, but as it turns out, IBM is getting a SAS version of the drive or using a SATA-to-SAS bridge. It doesn’t matter how it gets done. What does matter is that the single-level cell (SLC) drives that IBM has been peddling for two years are very expensive, but the new SandForce eMLC drives and IBM controllers are priced to sell.

As I explained back in May, the MLC flash technology is what we have in our cameras and thumb drives. SLC flash is more reliable, and the trick to putting MLC flash into enterprise production is to cram a lot of capacity into an MLC unit and then only allocate a portion of it to doing useful work. This way, as a memory cell starts to fade, the data can be moved to a new cell before it is lost and the faulty cell de-allocated. SandForce calls this flash memory detection and correction DuraClass, and it is not the only SSD vendor to come up with this idea, by the way. The basic SandForce drive has a maximum capacity of 512 GB and delivers 30,000 I/O operations per second (IOPS) using 4 KB data blocks for random reads and writes; the SSD has a sequential read/write transfer rate of 260 MB/sec using 128 KB blocks. This is a lot faster than the drives IBM has been peddling to date. IBM says that the SandForce drive is designed to be used in write-intensive applications for at least five years, with typical customer usage (with a higher percentage of the activity being reads) giving a much longer lifespan.

IBM offers the drive in two formats. The AIX and Linux operating systems can support 512-byte blocks as their underlying format, and if you do that, you get 200 GB of usable capacity (with the rest unallocated and reserved to deal with memory cell failures in the future). The IBM i operating system requires a 528-byte block size, and that gives you 177 GB of usable capacity. By the way, AIX and Linux both work with the 528-byte block size, so you can do it all the same and move operating systems around as you see fit. The AIX and Linux operating systems support either raw disk in 200 GB format or RAID mirroring performed by the operating system in 177 GB format for the new SSDs. The IBM i platform assumes you will use RAID mirroring, either RAID 0 mirroring of whole controller and SSD ensembles or RAID 5 or RAID 6 data protection within a single ensemble. (RAID 5 means striping across all four SSDs in the unit, while RAID 6 means striping across three drives in the set and keeping one as a hot spare.) You cannot mirror hard disks and SSDs against each other no matter what operating system you choose.

As you can see from the picture below, the new SSD controller/drive unit is a double-wide PCI Express peripheral card:

The SSD/SAS controller combo comes in three flavors. Feature 2053 is a low-profile PCI-Express 2.0 version that is designed for the Power 710, 720, 730, and 740 enter servers and their low-profile slots. (The Power 720 and 740 have four full-height PCI-Express 2.0 slots as well as four optional low-profile slots; the Power 710 and 730 only have four of the low-profile slots.) Feature 2054 is a full height version of the SSD/SAS controller combo that is intended for Power 720, 740, and 750 machines. Feature 2055 is a full height unit aimed at the Feature 5802 and feature 5877 PCI-Express I/O drawers, which link to Power Systems machines by 12X I/O adapters. You cannot put any of these new SSD/SAS controller subsystems in the Power 770, 780, or 795 machines or in any earlier Power5, Power5+, Power6, or Power6+ machines because the adapter is not supported. The SSD disk itself is feature 1996 when in the 528-byte format and feature 1995 when in the 512-byte format.

The individual SSD drives used in the new device cost $4,400 a pop in the entry machines, and $5,763 when aimed at the larger boxes and I/O drawers. (Why, you ask? Because IBM says so.) The SAS controller with the RAID and adapters for the SSD drives costs $3,054 on the smaller machines, and $4,000 on the bigger boxes and I/O drawers. So on an entry box, the controller plus four drives will run you a cool $20,654, while on a the bigger boxes and I/O drawers, you’re talking $27,052. That’s for 708 GB of storage and something on the order of 120,000 IOPS.

To cushion the blow, IBM is bundling up five controllers and 20 SSD drives and giving a discount. On the smaller Power Systems boxes, this bundle is called feature 4367 for AIX and Linux and feature 4377 for IBM i formats, and it costs $74,904. That’s a 27.5 percent discount off list price. On the bigger boxes and I/O drawers, the bundles are feature 4367 (AIX and Linux) and feature 4377 (IBM i), they cost $98,114, and that works out to the same 27.5 percent discount.

The SSD/SAS controller bundles require AIX 5.3, 6.1, or 7.1, IBM i 7.1, Red Hat Enterprise Linux 5.5 or the soon-to-be release 6, and Novell SUSE Linux Enterprise Server 10 or 11.

In related storage news, IBM is now formatting a fat 10K RPM, 2.5-inch SAS disk for Power Systems machines. Feature 1911 comes in the 528-byte format IBM i requires, which turns a 300 GB disk into a 283 GB unit. It costs $1,050 in single-unit quantities at list price. The drive is supported with IBM i 6.1.1 or 7.1 on Power 710, 720, 730, 740, 750, 770, 780, and 795 machines.

Both the new SSD/SAS controller combo and the 283 GB disk will be available on September 17.

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