Re: Backups with filesystem snapshots

On Mon, Aug 11, 2025 at 12:41:12PM -0400, Greg Sabino Mullane wrote:
> On Mon, Aug 11, 2025 at 9:01 AM Nick Cleaton <nick(at)cleaton(dot)net> wrote:
>
> If I take an instantaneous filesystem-level snapshot of the postgres
> data directory underneath a running postgres server, is that a safe
> backup without doing any pg_start_backup/pg_stop_backup ?
>
>
> Safe, yes[*], but not particularly recommended except for special cases, like
> spinning up a fast QA cluster. For backups, use a Postgres-aware battle tested
> system like pgBackRest that offers more flexibility and more safeguards.
>
> * Assuming your hardware/OS drivers are being honest with you about fsync
>
>
> starting up from that snapshot should look the same as recovering from an
> unclean postgres shutdown
> due to a kernel panic.
>
>
> Yes, for all practical purposes it would be identical. Technically more similar
> to pulling the plug on the server. :)

Also, be careful that any tablespaces are also in the same snapshot.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Do not let urgent matters crowd out time for investment in the future.