This is a message to confirm my thoughts / validate a possible approach.
In a situation where PGDATA and {XLOG, ARCHIVELOG} are on different SAN/NAS volumes and a backup is to be initiated do pg_start_backup and pg_stop_backup need to be used?
I am using snapshots of each volume for backup.
My thinking is that they are not needed (although I realise it is good practice).
As far as I can tell all they are doing is something like:
pg_start_backup:
- create backup label
- trigger checkpoint
pg_stop_backup
- remove backup label file
- creates backup history file
- trigger log switch
There is nothing in here that is *required* from a backup point of view. Am I missing anything?
The backup functions also set internal state in the database, so you can't just replace it with doing those operations manually. You do need to call those functions.