IBM delivers baby SAN

Share and share alike

fingers pointing at man

If you are an SMB customer and you have taken a shining to Big Blue's BladeCenter S blade box, the company has a new and better storage option for you today than you had yesterday. Starting today, IBM is shipping a SAS-based storage area network inside the chassis as an alternative to external Fibre Channel SANs that are also more expensive than the SAS configuration.

IBM and Hewlett-Packard are locked in mortal combat over the blade server market, and after years of trying to sell blades as a high-end product for data centers, both companies last summer announced variants of their respective BladeCenter and BladeSystem product lines aimed at small businesses. That wanna expand their revenues from blades.

But SMB shops are pretty much allergic to SANs, not just because of the expense, but also because of the complexity and despite the obvious benefits of using shared storage for a bunch of servers. That doesn't mean a SAN blade is a bad idea, which is why HP created one for its "Shorty" BladeSystem c3000 chassis, which runs on wall power and is designed for office environments.

IBM doesn't have storage blades per se, but IBM did have a disk storage module for linking up to six disk drives directly to a particular blade in its low-end BladeCenter S chassis, which has room for six blades and runs on wall power, or its high-end BladeCenter H chassis, which can hold 14 blades but requires 240-volt power. Today, IBM will announce that it has taken the RAID disk controller inside its DS3200 disk array and shrunk it down so it fits in the back of the BladeCenter S chassis, where the Ethernet and Fibre Channel switches go.

The chassis actually has room for two SAS RAID controllers, and they are linked in an active-active cluster that allows up to two of the SAS disk modules to be linked into a single 12-disk array with redundancy in the controllers. The SAN switches link to the disks in the modules and back to the blades as well through host bus adapters, creating what is functionally equivalent to a Fibre Channel SAN, although from much less expensive SAS components.

The upshot is that IBM's BladeCenter S customers can now contemplate using this baby SAN to support complex virtualization environments and their high availability software, which assumes SAN rather than dedicated storage in most cases. (For instance, the VMotion feature of VMware's ESX Server, which allows running virtual machine partitions to be teleported from one physical server to another, assumes that the servers are linked through shared storage. Basically, nothing is moving but memory state in a running VM and pointers back to the data in the SAN that actually comprise the bulk of the VM).

The economic argument for this baby SAS-based SAN won't be hard for IBM to make, at least compared to external SANs based on Fibre Channel networks. According to Scott Tease, worldwide marketing manager for the BladeCenter line at IBM, a pair of the SAS controllers costs $7,000. The disk modules are $800 a pop, and a 73 GB SAS disk costs $320, and each blade needs a two-port SAS HBA, which costs $139. (The BladeCenter S chassis costs $2,599).

When you add it all up, this SASy SAN costs $13,274. A pair of Fibre Channel switches can easily run $20,000, says Tease, and Fibre Channel HBAs for the six blades would run close to $5,000. Fibre Channel disks could be close to $1,000 a pop, and cabling is also not cheap. Basically, it comes to around $40,000. For many SMBs, their whole data center - more accurately called a data closet - costs less than this.

The baby SAN that IBM is announcing today supports Windows Server 2003 and Windows Server 2008, as well as the current releases of Linux from Red Hat and Novell. Ironically, customers using IBM's Power6-based dual-core JS12 and quad-core JS22 blades will have to wait until the first quarter of 2009 to get support for IBM's AIX 6.1 and i 6.1 operating systems. ®

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