On Sun, 2010-09-12 at 12:18 +0200, J. Roeleveld wrote: > On Sunday 12 September 2010 00:43:19 Bruce Momjian wrote: > > Gabe Nell wrote: > > > > That section has been removed from the current 9.0 docs because we are > > > > unsure it works. > > > > > > Hmm. So the only way to make a consistent backup from a standby server > > > is to shut down the standby first? Or is even that problematic? > > > > > > Would it change anything if we are able to guarantee that the > > > filesystem is snapshotted as a point-in-time snapshot by using LVM or > > > on Amazon EC2 by snapshotting an EBS volume? > > > > I believe a snapshot of the standby is fine even if it is running, just > > like on the master. > > How can you ensure the snapshot is in a consistent state if the server is > running? > > If a snapshot is taken between 2 updates in a single transaction, only half > of > this transaction is included in the snapshot. > I would never take an LVM (or similar) snapshot of an application that can't > be paused in a way to provide a consistent filesystem.
You need to read up on things like WAL and MVCC. Joshua D. Drake > > -- > Joost > -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 509.416.6579 Consulting, Training, Support, Custom Development, Engineering http://twitter.com/cmdpromptinc | http://identi.ca/commandprompt -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
