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Re: [Linux-cluster] Multipathing, CLVM and GFS





Christine Caulfield wrote:
Sajesh Singh wrote:


Christine Caulfield wrote:
Sajesh Singh wrote:
Centos 4.6
Cluster Suite

I am currently running a 2 node GFS cluster. The storage is provided via a fiber channel connection to the SAN. Each node currently has a single FC connection to the SAN. I would like to migrate to using dm-multipath with each node having dual fiber channel connections to the SAN. Can I assume that CLVM is aware of the /dev/dm-# devices that are used to access the multipathed devices? Are there any gotchas that are associated with installing the device-mapper-multipath software after the GFS cluster is up and running? Are there any howtos available for this type of setup?


clvmd works fine with dm-multipath devices. You will probably have to edit /etc/lvm/lvm.conf to exclude the underlying /dev/sd devices to stop it getting confused though.

You won't be able to do this with GFS mounted on the local node though, you'll have to umount it, setup dm-multipath, vgscan & remount. You CAN leave them mounted on other nodes while you do it.

Christine,
Should clvmd be restarted as well so that I can create new volume groups? I have device-mapper-multipath setup, but if I try to run pvcreate /dev/mapper/mpath1p1 the command just hangs without any errors.

No, you shouldn't need to restart clvmd unless you have an old version and have added or removed PVs (which might be the case if you have changed multipath devices).

pvcreate does very little in the way of cluster operations so it's probably worth checking it's not stuck writing to the dm device.

(sorry for the delay in replying, I've been away).


Thanks for the reply. All is working now. I did add PVs, but did not need to restart as it might just have been the clvmd cache. All was okay after refreshing the cache.




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