Re: Incrementally Updated Backups

On Sunday 12 September 2010 00:43:19 Bruce Momjian wrote:
> Gabe Nell wrote:
> > > That section has been removed from the current 9.0 docs because we are
> > > unsure it works.
> >
> > Hmm. So the only way to make a consistent backup from a standby server
> > is to shut down the standby first? Or is even that problematic?
> >
> > Would it change anything if we are able to guarantee that the
> > filesystem is snapshotted as a point-in-time snapshot by using LVM or
> > on Amazon EC2 by snapshotting an EBS volume?
>
> I believe a snapshot of the standby is fine even if it is running, just
> like on the master.

How can you ensure the snapshot is in a consistent state if the server is
running?

If a snapshot is taken between 2 updates in a single transaction, only half of
this transaction is included in the snapshot.
I would never take an LVM (or similar) snapshot of an application that can't
be paused in a way to provide a consistent filesystem.

--
Joost