Another question from John- multipath drivers

2 08 2007

Aloha Open Systems Guy,can you take another question from me? I’ve got some questions about OS-drivers for disk subsystems…What’s up with all the RDAC, MPIO/DSM, and SDD? I’ll try and keep things consistent by limiting my question to one OS (Windows Server 2003).

I’ve heard talk about SDD being superior for the ESS / DS8000 line of storage. It’s apparently not even available in an active/passive array. However, I’ve got a mid-range disk subsystem from IBM, the DS4300 Turbo model.

Until tonight I thought there was only a single choice of multi-pathing driver for me, RDAC. However, when I went about installing my first Windows OS to be SAN-connected I ran into all kinds of new information like SCSIport and STORport and now MPIO / DSM.

Can you help de-mystify this enigma for me?

Mahalo nui loa,

Certainly! Always happy to get more questions. I’m a chronic sufferer of writers block, so your questions help by providing material ;)

Each vendor dictates the support they provide for multi-path drivers, and going outside these constraints is possible, but will usually void the warranty. My experience with IBM is that they usually support something out of the box if it works, or in special cases if it can be made to work. Since they only support RDAC with the DS4000 series, I’ll bet that nothing else would work. Whether through design or technical limitation, I do not know, but I suggest that you stick with the driver they recommend.

The only limitation to RDAC is that it does not dynamically load balance- however in terms of failover protection, it’s bullet-proof.

edited to add: The other drivers you mention are supported on other IBM systems,  by the way. 




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