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RHEL4 with dm-multipath on root


I got a mail today from another group working with Linux servers on Dell PE2950's. They have HP EVA boxes as their SAN, instead of our EMC DMX-3/4, and wanted to know how we got multi-pathing to work in Oracle's Enterprise Linux 4, update 5. They had heard that it was terrible and were thinking of using RHEL/OEL 5u2 instead. I told them, we were using PowerPath for this reason, and because EMC would only support us iff we used PowerPath. dm-multipath was not supported. Hmmm. Fair enough...

While dm-multipathing is available in OEL 4u5, you have to go through some tricks to get it to support your root volume over dm-multipath. TuxyTurvy has instructions and people report it works. The trick he uses is to make a custom initrd image. Another solution may be to use HP StorageWorks for Linux or HP's own dm-multipath.

Update: We going a different route... We'll install ESX 3.5 on the Dell servers and install Linux in VMs only, virtualizing the whole setup. ESX is compatible with the HP EVA and provides us with a nice path for the future. The Linux LSI drivers in the VM will work nicely with ESX and SAN and using VMware prevents the need for multipath HBAs.
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