IBM Adds Disk Storage Options for i Shops

Published: December 15, 2008

by Timothy Prickett Morgan

Given its single-level storage heritage, getting the AS/400 and its successor machines to think of disk storage and main memory separately like other servers do has been something of a tricky bit of coding. But modern disk subsystems have their advantages, and companies support many different kinds of servers and therefore want to consolidate their storage as much as possible. The i platform can't be left out as the red-headed stepchild. Well, not all the time, anyway, and particularly not in the unified Power Systems world.

To that end, IBM last week made a couple of announcements that bring support for a popular midrange disk array, the DS3200, and IBM's virtual storage controller, the SAN Volume Controller, to the i platform.

The DS3200s were launched in April 2007 for System x rack and tower and BladeCenter blade servers, and they are a collection of SAS disks with a SAS or Fibre Channel interface back to the servers. And showing just how far IBM has fallen in decades, the sales manual does not specify what operating systems are supported with this device, which is an unconscionable sin for an IBMer doing the documentation to have committed. So I don't actually know, as I write this, whether the DS3200 supported native attachment to System i or Power Systems i boxes. But I suspect not, or there wouldn't be much of a point of an announcement last week for support of the DS3200 on Power6-based BladeCenter machines running i 6.1, AIX 6.1, and Linux.

The DS3200 is a 2U disk enclosure that has a dozen bays for hot-swappable 3.5-inch SAS drives. The 3 Gb/sec SAS interface is supported on the drives, and the unit contains a RAID disk controller that supports RAID 1, 3, 5, and 10. The unit can have up to two RAID controllers, which can be both active or acting redundantly (with one backing the other up). Up to three hosts can be connected with redundant SAS links to the box, and the controllers come with the typical modern disk array software, such as FlashCopy and VolumeCopy data replication. Using 300 GB SAS disks, the DS3200 supports up to 3.6 TB of disk capacity, and up to three more EXP3000 enclosures can be added to the unit for a total of 48 drives and 14.4 TB of capacity. IBM offers 73 GB, 146 GB, and 300 GB SAS drives in the DS3200. The unit also supports SATA disks in 500 GB and 1 TB capacities; the i operating system does not support SATA drives as far as I know, but Linux and AIX do.

Anyway, the Power6-based JS12 (single-socket, dual-core) and JS22 (two-socket, dual-core) blade servers can now link to the DS3200 either through a SAS expansion card (feature 8250); customers have to also get the BladeCenter SAS connectivity module (feature 3267) to link to BladeCenter S, BladeCenter H, or BladeCenter E chasses. If you want redundant SAS paths, you have to buy two of these modules for the chassis. On the BladeCenter S, the DS3200 IBM's AIX and i operating systems as well as Linux and the Virtual I/O server (VIOS) used with all three of these operating systems is supported. VIOS, which virtualizes disk and network I/O on Power-based machines, which can be used to consolidate storage for multiple logical partitions on a single machine, and which itself runs inside a logical partition, is important to i shops because i 6.1 is not supported natively on the JS12 and JS22 blades (as Linux and AIX are), but only runs in conjunction with VIOS. IBM made the support for the JS12 and JS22 blades available on December 9, and presumably there is a patch for the disk array so it recognizes the host and a matching one for the blades so the operating systems or VIOS can see the DS3200.

IBM also announced last week that i 6.1 servers using the VIOS program on any Power6-based server can use VIOS to link i 6.1 to the SAN Volume Controller (SVC) or its entry knock-off, the SVC Entry Edition. The SVC is what is known as an out-of-band storage virtualization appliance, which allows multiple kinds of disk arrays to link to multiple kinds of servers in a virtual rather than a physical way. For big data centers with complex server infrastructure, getting the i platform to play with the SVC is important. But for smaller customers, this is probably not particularly useful. Anyway, this support became available on December 9.

And a tiny thing more happened last week as well. As IBM said it would do back in October, when it finally converged the System i and System p lines for good with the 83XX line of boxes (replacing 940X machines that had the System i or Power Systems i Edition name and their respective upgrade restrictions), the single-core version of the Power Systems 520 i Edition (known as 9407-M15 and having user-based pricing for the operating system) can be converted to a Power Systems generic edition (known as 8203-E4A in the converged product). This conversion, which is not particularly useful unless IBM requires customers to be on an 8203-E4A machine to get a future system upgrade (which is a possibility for future Power6+ machines, but probably not for Power7 machines, which will have a different package for processor technology) or if you want to resell the box as an AIX-only machine (which the i Edition machine was not, even though you could, in theory, but AIX on a logical partition). It sounds to me like this paper conversion of the machine is a way to make it an AIX box for resellers who might be sitting on inventory, but if they did that, they would be sacrificing the money they paid (even at wholesale prices) for an i 6.1 box. This doesn't make a lot of sense to me, either. But neither did a lot of the financial shenanigans that have defined the last two decades of the global economy. Just to be clear: your i 6.1 licenses work after the conversion. So don't be nervous about that.

Anyway, there is some downtime as the machine's BIOS is updated with the new machine type information, so be aware of that if you decide to do it. The model conversion will be available on January 16, 2009.

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