Subject: Re: Error message in wal_log for Streaming replication
From: Jeff Davis <pgsql@j-davis.com>
To: Nimesh Satam <nimesh.zedo@gmail.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <AANLkTikX6DwvJseUST-dvXV8uBmSZQRmLKTrDmEowjhe@mail.gmail.com>
References: <AANLkTikX6DwvJseUST-dvXV8uBmSZQRmLKTrDmEowjhe@mail.gmail.com>
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Date: Tue, 05 Oct 2010 14:05:17 -0700
Message-ID: <1286312717.9636.10.camel@jdavis-ux.asterdata.local>
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On Tue, 2010-10-05 at 14:41 +0530, Nimesh Satam wrote:
> We have been trying to implement the streaming replication on one of
> our test servers. We have set archive_xlogs to on. But on the standby
> server,  when we start the database we get error the following errors:
> 
> LOG:  shutting down
> LOG:  database system is shut down
> LOG:  database system was shut down in recovery at 2010-10-05 05:05:27
> EDT
> LOG:  entering standby mode
> cp: cannot stat
> `/home/postgres/archive_xlogs/000000010000000D00000036': No such file
> or directory
> LOG:  consistent recovery state reached at D/36000078
> LOG:  database system is ready to accept read only connections
> LOG:  invalid record length at D/36000078
> cp: cannot stat
> `/home/postgres/archive_xlogs/000000010000000D00000036': No such file
> or directory
> LOG:  streaming replication successfully connected to primary
> 
> The file "000000010000000D00000036" is seen in pg_xlog folder of the
> primary database, but is not yet pushed to the archive location.
> 
> Can you let us know what the error means and if we are doing anything
> wrong?

[ this question is more appropriate on pgsql-general ]

Those aren't postgres error messages, those are error messages generated
by "cp".

See:
http://www.postgresql.org/docs/9.0/static/archive-recovery-settings.html

"The command will be asked for file names that are not present in the
archive; it must return nonzero when so asked."

So, it is safe to ignore those errors.

Personally, I would use a restore_command that is silent when the file
doesn't exist so that it doesn't pollute your logs. I'm not sure why the
documentation suggests "cp".

Regards,
	Jeff Davis