On Wed, Jun 19, 2013 at 6:20 PM, Stephen Frost <sfrost@snowman.net> wrote:
> * Claudio Freire (klaussfreire@gmail.com) wrote:
>> I don't see how this is better than snapshotting at the filesystem
>> level. I have no experience with TB scale databases (I've been limited
>> to only hundreds of GB), but from my limited mid-size db experience,
>> filesystem snapshotting is pretty much the same thing you propose
>> there (xfs_freeze), and it works pretty well. There's even automated
>> tools to do that, like bacula, and they can handle incremental
>> snapshots.
>
> Large databases tend to have multiple filesystems and getting a single,
> consistent, snapshot across all of them while under load is..
> 'challenging'. It's fine if you use pg_start/stop_backup() and you're
> saving the XLOGs off, but if you can't do that..
Good point there.
I still don't like the idea of having to mark each modified page. The
WAL compressor idea sounds a lot more workable. As in scalable.