Hi,
I'm currently in the process of upgrading a RHEL 3 cluster to RHEL 4,
and I haven't been able to figure out how to use snapshots in a proper
way. We have other RHEL 4 systems using LVM2, and I use snapshots with
ext3 for backup with great success on those. As the demand for uptime
on this particular cluster is cruicial (and regular filebackup using
tar is way too slow!) I was hoping to accomplish the same kind of
snapshots with GFS1 and RHEL 4 as with ext3.
My test-environment consists of 3 VM's in a VMware Server 1.0.3
environment, using DLM and one GFS filesystem on the VM's. Fencing and
connectivity is working just fine, but when I try to use snapshots
things go wrong.
I try to initiate the snapshot via
[root@gfs1 Scripts]# lvcreate -L500M -s -n snap /dev/GFS/LV1
Logical volume "snap" created
When I try to mount the snapshot (in the same way as I do with an ext3
snapshot) it does not seem to work
[root@gfs1 Scripts]# mount -t gfs
/dev/mapper/GFS-LV1 on /mnt/GFS type gfs (rw)
[root@gfs1 Scripts]# mount -t gfs /dev/GFS/snap /mnt/GFS-snap
mount: File exists
Also - when I try to do changes in the /mnt/GFS filesystem after
creating the snapshot, there does not seem to be any changes in the
snapshot when I check the graphical interface of LVM (it says Snapshot
usage: 0%). Attributes are "swi-a-" and GFS (clustered) according to
LVM.
I assume I am missing something vital here, but I haven't been able to
find the documentation which explains this in an easy manner.
Any inputs will be highly appreciated!
Best regards,
Oliver Olsen
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