Re: Deleting WAL archives and pg_xlog when there is not a shared drive

On Tue, Dec 11, 2012 at 9:37 AM, Eng. AlSamman <iyamen(at)live(dot)com> wrote:
> I am trying to implement a high-availability cluster using only two nodes,
> without any shared disk storage.
>
> In my implementation, the primary database has continuous archiving set up
> to a directory residing on the second node, where the standby database is.
> Streaming replication is also established between the two. When failover
> occurs, the standby is promoted to primary, and will start its continuous
> archiving but now on a directory on the other (former primary) node.
>
> Call the primary node N1 and the standby N2. When N1 fails and N2 is
> promoted, can I safely delete the archive logs stored on N2 (which were
> archived by N1 when it was primary?)?

You can.

> Also, when N1 is started but now it
> must become a standby, I run pg_start_backup() on N2, sync the data
> directories (except pg_xlog) then pg_stop_backup() on N2.

You must not start N1 before you have done a base backup
(pg_start_backup()/pg_stop_backup()).

> Can I safely
> delete everything under pg_xlog in N1 BEFORE starting it since anyways they
> won't be used (what will be used instead is the archive directory on N1
> which is being populated by N2)?

You can delete everything under N1 data directory before making a base backup.

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