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[linux-lvm] Re: [PERFORM] backup/restore - another area.

On Thu, 16 Oct 2003 10:09:27 -0700
Josh Berkus <josh agliodbs com> wrote:

> Jeff,
> > I left the DB up while doing this.
> >
> > Even had a program sitting around committing data to try and corrupt
> > things. (Which is how I discovered I was doing the snapshot wrong)
> Really?   I'm unclear on the method you're using to take the snapshot,
> then; I seem to have missed a couple posts on this thread.   Want to
> refresh me?

I have a 2 disk stripe LVM on /dev/postgres/pgdata/

lvcreate -L4000M -s -n pg_backup /dev/postgres/pgdata
mount /dev/postgres/pg_backup /pg_backup 
tar cf - /pg_backup | gzip -1 > /squeegit/mb.backup 
umount /pg_backup;
lvremove -f /dev/postgres/pg_backup;

In a nutshell an LVM snapshot is an atomic operation that takes, well, a
snapshot of hte FS as it was at that instant.  It does not make a 2nd
copy of the data.   This way you can simply tar up the pgdata directory
and be happy as the snapshot will not be changing due to db activity.

Jeff Trout <jeff jefftrout com>

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