FW: LVM level snapshot backup and restore

[Geofrey Rainey]

Sorry, a few typo's fixed from my previous response..

-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Geofrey Rainey
Sent: Friday, 12 June 2009 2:54 p.m.
To: General Red Hat Linux discussion list
Subject: RE: LVM level snapshot backup and restore

I don't think a snapshot image can be used to create a backup of a
logical
Partition by itself because the snapshot image only contains changes
(actually I think it contains the copies of the old blocks - like the
redo logs in a database), thus the original partition is needed to
restore the data and if you've destroyed this with your partition
extension, the snapshot won't help. Therefore, I'd be inclined to backup
your lvm partition
Like the following (this is how I do it):

1. create a snapshot file - this can probably be quite small (depending
on usage but 1G is probably enough)

lvcreate -s -L 1G -n <name of snapshot>
/dev/<volume_group>/<logical_volume_name>

2. then backup your partition with something like this:

dd if=/dev/<volume_group>/<name of snapshot> of=<path/lvm_backup.img>
bs=1M

3. if you need to restore, do the following:

dd if=< path/lvm_backup.img of=/dev/<volume_group>/<logical_volume_name>

Of course you'll need as much space as the original partition for this
but that's the only solution I think.


-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Narayanan,
Karthikeyan
Sent: Friday, 12 June 2009 10:55 a.m.
To: redhat-list at redhat.com
Subject: Re: LVM level snapshot backup and restore

Hi There,

 

I have a production server which requires a logical volume expansion.
The file system which requires expansion is not yet placed in the backup
rotation. Before expanding the file system, I wanted to setup a LVM
snapshot to ensure we have a proper backup in case of a failure during
expanding the volume. Can anyone here describe me the steps to do?

 

Thanks

Karthik

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