Similarly you can rsync a Postgres data directory safely while the db is running, with the caveat that you likely lose any data written while the rsync is running. And if you want that data, you can get it with the WAL files.

It’s been years since I needed to do this, but if I remember right, you can clone an entire pg db live with a `pg_backup_start()`, rsync the data directory, pg_backup_stop() and rsync the WAL files written since backup start.

For moving DBs where I'm allowed minutes of downtime I do rsync (slow) first from the live, while hot, then just stop that one, then rsync again (fast) then make the new one hot.

Works a treat when other (better) method are not available.

MSSQL also offers a virtual backup device interface that 3rd party tools can implement.

https://learn.microsoft.com/en-us/sql/relational-databases/b...