Re: Backups with filesystem snapshots

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. :)

Cheers,
Greg

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