What you seem to be describing is the mirror target for device mapper. Another alternative would be to setup a software raid using multipath'd luns. SANVOL1 SANVOL2 | | \ / \ / \ / MPATH1 MPATH2 \ / RAID 1 DEV | PV | VG | LV That might work -C On Sat, Apr 30, 2011 at 10:08 AM, urgrue <urgrue@xxxxxxxxxxx> wrote: > But, how do you get dm-multipath to consider two different LUNs to be in > fact two paths to the same device? > I mean, normally multipath has two paths to one device. > When we're talking about san-level mirroring, we've got two paths to two > different devices (which just happen to contain identical data). > > On 30/4/11 11:47, Kit Gerrits wrote: >> >> 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 > > -- > 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