Re: [Xen-users] xen storage options - plase advise

[James Pifer <jep@xxxxxxxxxxxxxxxx>]

> > Yes, file based domU's are currently on ocfs2 on a SAN. 
> > 
> > I don't do any snapshotting right now, but that's not to say I won't
> > want to some day.
> 
> Yes, but you _want_ to be able snapshot your domUs, because of
> "Hot-backup" of running domUs.

This is a bit off the topic of my original post, but can you elaborate
just a little on this? How do you use snapshot for hot-backup? 

> 
> >  My goal is to get to a point where things are stable
> > and I can run something to manager everything, ie Orchestrate,
> > Convirture, something to manage restarting/migrating domU's when one of
> > the servers has problems. Or I just need to have a server down for
> > maintenance.
> 
> You're searching for openQRM ;-)

Thanks for this suggestion. Glanced at it briefly and will definitely
look at it some more. Have you looked at convirt? I liked how that
looked, but HA features appear to cost extra. 

> 
> > So in general terms, how would I setup LVM (clvm)? Let's say I have two
> > servers (in this case running sles11). Each server has the SAME
> > vdisk(LUN) from our Xiotech SAN assigned to it for storage. Let's say
> > it's a 400gb vdisk. If I add additional servers, they too would be
> > assigned the same vdisk. Similarly, I could add additional vdisks when
> > more storage is required. 
> 
> You have to care that _EVERY_ dom0 is "seeing" the Storage-LUN!
> 
> If your hosts are able to connect to this storage ALL Hosts should be
> able to use this Volumes (LVols)
> 
> > 
> > Anyway, on the first server I setup LVM. Somehow the second server would
> > also see that as lvm and be able to mount it?
> 
> pvscan 
> vgscan 
> vgchange -ay 
> 
> should be enough that ALL Hosts could start the domUs residing in this
> LUN / VG....

Ok, I may try this tomorrow, but just to clarify, doing this does NOT
allow me to use snapshotting? Why is that?

So if I have the same 400gb device(LUN) assigned to each server.
I create a logical volume
I create a file system on that logical volume
Mount that on each server using the same name for the mount point.

So essentially each server would see /data which is the file system on
the LVM. Under /data/images I could store my file based domUs. That's
essentially what I'm doing right now on ocfs2. Does snapshotting work on
ocfs2? If so, how are they different in terms of snapshotting?

Thanks,
James


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