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 ?
>
> 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.

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