On Mon, Aug 11, 2025 at 9:01 AM Nick Cleaton <nick@cleaton.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. :)
