Re: [Xen-users] Using lvm for domUs

[Nico Kadel-Garcia <nkadel@xxxxxxxxx>]

Goswin von Brederlow wrote:
> Nico Kadel-Garcia <nkadel@xxxxxxxxx> writes:
>
>   
> > Goswin von Brederlow wrote:
> >     
> > > If you have enough disks/partitions you can make one VG per domU and
> > > share that for dom0 and domU using cluster lvm (clvm) to keep them in
> > > sync. Instead of real disks/partitions you can run lvm in dom0, create
> > > a LV per domU and run lvm on it again. But then you have to
> > > specifically include the first lvm LVs in lvm.conf and run vgscan
> > > twice. I think that should work.
> > >
> > >       
> > Have you tried this? For various reasons, I'm looking at using iscsi
> > or clvm for having commong storage and permitting live migrations, and
> > for snapshotting the LVM's for backup purposes. (LVM snapshots and
> > rsnapshot, a combination made in heaven!)
> >     
> I was thinking about drbd0.8 active-active with clvm but drbd0.8
> caused crashes. And drbd0.7 can't do active-active.
>
> But with iscsi and clvm there should be no problem. clvm is just a
> little daemon that basically runs vgscan on all hosts whenever you
> change something.
>
>   
> > > We use lvm inside LVs here on a HA cluster but the inside lvm is
> > > exclusively for the domU. No sharing with dom0. The dom0 lvm is so we
> > > can resize and create/destroy LVs on the fly, the inside lvm is
> > > because all our servers are setup the same.
> > >
> > >       
> > Unfortunately for me, my Dom0 hardware does not have the CPU's for
> > full virtualization, so access to backup media has to go through Dom0
> > or be pushed over the network. And the network or Xen usage seems to
> > double my backup timef, so I *need* Dom0 to be able to access the hard
> > drive contents of DomU.
> >     
> You can always create LVs in dom0 and export them as sda1/2/3/... to
> domU. You have to reboot domU to resize anyway. That way you can then
> snapshot them in dom0, mount the snapshot and run your backup.
>   
I do that now, but I can't do a raw install that way using virt-install 
or virt-manager, so doing that virst install is a pain in the neck to 
get a working image. The jailtime.org images are good, but not so useful 
for non-RPM based OS's.
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