On Mon, 22 Apr 2002 23:47:55 BST, Matthew Toseland said: > lvcreate -n <snapshotname> -L 500M -v /dev/<vgname>/<partition name>
You missed the -s flag. From 'man lvcreate' (LVM 1.0.3):
-s, --snapshot
Create a snapshot logical volume (or snapshot) for an existing, so
called original logical volume (or origin). Snapshots provide a
'frozen image' of the contents of the origin while the origin can still
be updated. They enable consistent backups and online recovery of
removed/overwritten data/files. The snapshot does not need the same
amount of storage the origin has. In a typical scenario, 15-20% might
be enough. In case the snapshot runs out of storage, use lvextend(8) to
grow it. Shrinking a snapshot is supported by lvreduce(8) as well. Run
lvdisplay(8) on the snapshot in order to check how much data is allo
cated to it.
> dd if=/dev/<vgname>/snapshotname of=/usr/local/temp/snapshot.img bs=1M
> lvremove -f /dev/<vgname>/snapshotname
The rest of this looks OK (although I've *NOT* tried it myself). I'm not
sure what the granularity of the snapshot is - whether you need to allocate
space for each block that's modified, or each 4M segment, or what...
--
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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