On Mon, 2009-03-23 at 22:34 -0500, Vu Pham wrote:
> Paul Dugas wrote:
> > I apologize if this has been covered already or is written up elsewhere
> > but I can't seem to find it. I've got a couple of AoE volumes that I'm
> > using for LVM VGs. They have GFS filesystems on LVs that are sized to
> > fill 90% of the the VGs; 10% space left over for snapshots. I have 4
> > CENTOS 5.2 machines clustered and mounting the GFS filesystems. That's
> > working well.
> >
> > Having used LVM snapshots in non-cluster environments before, I figured
> > I'd just use the same logic for backing up the volumes; lvcreate -s,
> > mount, backup, umount, lvremove. This quickly fell apart and I started
> > to think about it more. I ended up wondering how snapshots of the
> > volume could ever really work without coordinating with the other
> > nodes.
> >
> > My question is this. Should I be able to use snapshots on clustered
> > volumes like this? If not, are there plans to support it later? If so,
> > can someone point me to a working example?
> >
>
> I think you have to freeze the GFS volume before you create a snapshot,
> then you unfreeze it. man gfs_tool
That's what I was looking for. Much thanks for getting me further but I
think I'm still missing a step. Currently, this is what my "pre-backup"
script is doing:
COOKIE=`gfs_tool list | egrep " $LK_TBL_NM.[0-9][0-9]*\$" | awk '{print \$1}'`
gfs_tool freeze $COOKIE
lvcreate --size ${SIZE} --snapshot --name SNAP /dev/${VG}/${LV}
gfs_tool unfreeze $COOKIE
gfs_fsck -y /dev/${VG}/SNAP
mount -t gfs -o ro,lockproto=lock_nolock /dev/${VG}/SNAP ${MNTPT}
I'm getting a "File Exists" error from the mount which I believe is
because I'm trying to mount both the device and the snapshot at the same
time and they share the same lock-table-name. Now that I think of it,
I don't really need to mount the original version of the file system so
I may be able to move past this hitch but I'm wondering if there's a
good way to address this? Could I rename the lock table via "gfs_tool
sb /dev/${VG}/$SNAP table $LK_TBL_NM.SNAP" to get around it? Would that
change be cleared when the snapshot is removed?
P
--
Paul Dugas - paul@dugas.cc - 404.932.1355
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