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 ?
It seems like it should be, so long as I get an atomic snapshot that includes both data and wal, because starting up from that snapshot should look the same as recovering from an unclean postgres shutdown due to a kernel panic.
We once restored a whole-system VMware snapshot to a new VM (new IP address and everything). When I logged in, PG started up without a hiccup; it took a couple of minutes while WALs rolled forward, but that's to be expected.
Postgresql didn't (and doesn't) know anything about when snapshots are taken.
