On Wed, Sep 7, 2016 at 5:00 PM, Jim Nasby <Jim.Nasby@xxxxxxxxxxxxxx> wrote: > 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). > -- I'm still wondering why my advice to just subscribe a new cluster on the master machine was just ignored by OP. Postgresql already has a pretty reliable method for doing what the OP wants using pg_basebackup. Using rsync etc is like reinventing the wheel imho. -- To understand recursion, one must first understand recursion. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
