On 9/2/16 11:44 AM, David Gibbons wrote:
rsync -va /var/lib/pgsql/ /var/lib/pgsql2/ service postgres stop rsync -va /var/lib/pgsql/ /var/lib/pgsql2/ The second rsync will only copy the deltas from the first, it still has to go in and determine what needs to be copied/what changed but the bulk of it can be prepared/migrated before the actual downtime window.
That is NOT safe. The problem is it allows rsync to use mtime alone to decide that a file is in sync, and that will fail if Postgres writes to a file in the same second that the first rsync reads from it (assuming Postgres writes after rsync reads). You need to add the --checksum flag to rsync (which means it will still have to read everything that's in /var/lib/pgsql).
-- Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX Experts in Analytics, Data Architecture and PostgreSQL Data in Trouble? Get it in Treble! http://BlueTreble.com 855-TREBLE2 (855-873-2532) mobile: 512-569-9461 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
