Re: [ADMIN] question on warm standby

[Database Administrator]

-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Thursday, November 13, 2008 10:06 PM
To: Mark Steben
Cc: pgsql-admin@postgresql.org
Subject: Re: [ADMIN] question on warm standby

"Mark Steben" writes:
> I am running postgres 8.3.4 on master(mymachine) and slave(hummer). I am
> attempting to implement warm standby.
> 1. On mymachine I have the following archive_command:
> Scp %p postgres@hummer:/var/backups/archlog/%f
> (scp has been set up with ssh keys so that password
> Is not required for postgres user)
> This works fine. Copies wal logs to the /var/backups/archlog
directory.

Okay ...

> 2. Before I attempt pg_standby or some other wait script on hummer I
have
> Used a simple cp command in my recovery.conf file to manually
restore
> My first set of updates:

> restore_command = 'cp /var/backups/archlog/%f %p'

This looks fine too, perfectly standard.

> From the doc I am assuming that %f should be the file name(s) of
the
> Wal log in /var/backups/archlog/ to be copied into the
> /*/*/*/*/pg_xlog directory referenced by %p
> But %f seems to be referencing current wal log names in
> /*/*/*/*/pg_xlog. I am getting messages like:

> cp: cannot stat `/var/backups/archlog/0000000600000003000000D2':
> No such file or directory

Are you sure that's an error? As per the docs, the restore_command will
sometimes be asked for files that aren't there. I'd expect one or two
such failures in a restore session.

> 0000000600000003000000D2 is an actual wal log in hummer's
> /*/*/*/*/pg_xlog directory.

Yeah, but is it in hummer's /var/backups/archlog ?

[Mark Steben] No it's not. But there are wal logs in there
Copied successfully from the master that I expected to be
Applied to the database and were not

regards, tom lane


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