Re: ZFS filesystem - supported ?

On 10/25/21 13:13, Stephen Frost wrote:
> No, it's not- you must also be sure to archive any WAL that's generated
> between the pg_start_backup and pg_stop_backup and then to be sure and
> add into the snapshot the appropriate signal files or recovery.conf,
> depending on PG version, to indicate that you're restoring from a backup
> and make sure that the WAL is made available via restore_command.
>
> Just doing stat/stop backup is*not* enough and you run the risk of
> having an invalid backup or corruption when you restore.
>
> If the entire system is on a single volume then you could possibly just
> take a snapshot of it (without any start/stop backup stuff) but it's
> very risky to do that and then try to do PITR with it because we don't
> know where consistency is reached in such a case (we*must* play all the
> way through to the end of the WAL which existed at the time of the
> snapshot in order to reach consistency).
>
> In the end though, really, it's much, much, much better to use a proper
> backup and archiving tool that's written specifically for PG than to try
> and roll your own, using snapshots or not.
>
> Thanks,
>
> Stephen

Stephen, thank you for correcting me. You, of course, are right. I have
erroneously thought that backup of WAL logs is implied because I always
back that up. And yes, that needs to be made clear.

Regards

--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com