With dual-controller arrays, dm-multipath keeps checking if the current device is still responding and switches to a different path if it is not. (for examply, by reading sector 0) With SAN failover, you may need to tell the secondary SAN LUN to go into read-write mode. Unfortunately, I am not familiar with tying this into RHEL. (also, sector 0 will already be readable on the secundary LUN, but not writable) Maybe there is a write test, which tries to write to both SANs The one which allows write access will become the active LUN. If you can switch your SANs inside 30 seconds, you might even be able to salvage/execute pending write operations. Regards, Kit -----Original Message----- From: linux-cluster-bounces@xxxxxxxxxx [mailto:linux-cluster-bounces@xxxxxxxxxx] On Behalf Of urgrue Sent: zaterdag 30 april 2011 11:01 To: linux-cluster@xxxxxxxxxx Subject: How do you HA your storage? I'm struggling to find the best way to deal with SAN failover. By this I mean the common scenario where you have SAN-based mirroring. It's pretty easy with host-based mirroring (md, DRBD, LVM, etc) but how can you minimize the impact and manual effort to recover from losing a LUN, and needing to somehow get your system to realize the data is now on a different LUN (the now-active mirror)? -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
