[email protected] wrote on 03/11/2011 12:27:40 PM:
> I'm trying to use LVM within virtual machines using volumes from my SAN.
> This works pretty well, except that when any RHEL physical host on the
> fabric reboots (in my case Xen Dom0, am migrating to KVM), LVM is
> autoconfigured on the host, which poses a massive problem when the
> virtual machine tries to start up. Is there any way in RHEL 5 (or 6) to
> mark an LVM group as belonging to a specific hostname? I use LVM on the
> physical hosts themselves, so I can't disable it, though I could setup a
> manual config file for LVM I suppose.
>
> What is the recommended course of action in the case of LVMs and SANs
> (even without VMs it is a problem)? Has this problem been fixed in 6?
> I've googled quite a bit on the problem but haven't found any real good
> information on dealing with this problem. I can't think I'm the only
> one with a SAN fabric.
I realize I'm a bit late to the discussion, and it seems you did already
get answers along this lines, but thought a "us too" might help.
We've been handling the disks in our Xen-based virtualization deployment
the same way you seem to be. The OS scans all disks and makes the volumes
available, i'm assuming, because its a nice "zero config" type of setup
that works well as a default. When we ran into this problem it worked out
well for us that we utilize HP hardware. The internal drives
are /dev/cciss/c0dX and were not multipathed. Everything from the SAN
was /dev/sdX and multipathed. We did a couple of things to make this
clean.
1: Turned on a filter for dm and sd devices inside lvm.conf:
# Exclude the multipath devices:
filter = [ "r|/dev/sd*|", "r|/dev/dm*|" ]
2: Turned off friendly names in multipath so that all disks would have the
same name on every system
With the internal drives being cciss devices we were also able to use LVM
on the host systems without having funkier rules.
We want LVM in our guests for many of the same reasons Chris Adams
mentioned.
-greg
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