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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>
http://www.jefftrout.com/
http://www.stuarthamm.net/



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