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Re: [Xen-users] does live migration require a cluster aware filesystem?

To: "Fajar A. Nugraha" <fajar@xxxxxxxxxxxxx>
Subject: Re: [Xen-users] does live migration require a cluster aware filesystem?
From: "Chris Fanning" <christopher.fanning@xxxxxxxxx>
Date: Wed, 7 Nov 2007 10:53:54 +0100
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
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I am under the impression that live migration requires the domU's de
be on block devices to work properly.
You might want to look at AoE.


On 11/7/07, Fajar A. Nugraha <fajar@xxxxxxxxxxxxx> wrote:
> Tomoki Taniguchi wrote:
> > On Nov 6, 2007 4:41 PM, Fajar A. Nugraha <fajar@xxxxxxxxxxxxx> wrote:
> >
> >> Tomoki Taniguchi wrote:
> >>
> >>> I can't seem to get find a straight answer to this question,
> >>> so i decided to ask it directly.
> >>>
> >>> If i want to do a live migration between two xen servers which has the 
> >>> domainU
> >>> filesystem shared to them using nbd, does the filesystem have to be
> >>> cluster aware like
> >>> gfs?  or can it be ext3 since technically the two servers should never
> >>> be writing to
> >>> the filesystem at the same time?
> >>>
> >>>
> >> If you store domU disks as files on dom0, then yes, you need a cluster
> >> file system.
> >> If you store domU disks as LVM (or other block device) on dom0, then no.
> >> Both dom0 involved in migration simply need to have access to the same
> >> block device. For example, you can have a server exporting LVs via
> >> iscsi, and several dom0's using them as domU storage.
> >>
> >
> > thank you.  can i assume this applies to nbd shared devices as well?
> >
> >
> Yes.
> >>> I was thinking since windows servers with ntfs filesystems doesn't
> >>> seem to have a problem,
> >>>
> >>>
> >> Really? Are you saying that two windows servers can mount the same
> >> ntfs-formatted block device at the SAME TIME without a problem?
> >>
> >
> > no what i mean is that it is possible to do a live migration of windows
> > domUs. and as far as i know NTFS is not cluster-aware.  so it stands
> > to reason that ext3 should be able to with stand a live migration as well.
> >
> >
> Perhaps I misunderstood your question.
> If you store your domU storage as files on dom0, then dom0 filesystem
> needs to be cluster aware for live migration to work.
> However, no such requirement apply for domU. So if your domU is just a
> normal, non-cluster server, then ext3 will work just fine on domU.
> Regards,
> Fajar
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