Re: WARM standby with pg_standby

Hi again,

After copying a new dump of the MASTER cluster data and starting the SLAVE with this data, I now get:

Database cluster state: in production
..
Minimum recovery ending location: 0/0

Still not exactly as expected, I guess. The log says things like :

"cp: cannot stat `/psql_archive/00000001.history': No such file or directory"

By the way, one of these lines each second!

"2010-04-09 09:09:49 IST FATAL: the database system is starting up"

Any help appreciated.

-dennis

--
Geysir IT
dth(at)geysirit(dot)dk
http://geysirit.dk
+45 31 51 60 00

On 08/04/2010, at 18.36, Kevin Grittner wrote:

> Dennis Thrysøe<dth(at)geysirit(dot)dk> wrote:
>
>> 1) The master keeps writing WAL files even though I'm quite sure
>> nothing is happening. This seems like a large waste of diskspace?
>
> What is your setting for archive_timeout? This limits how long
> before a WAL file is sent. You could extend the time, although that
> means that in case of a failure, you might not be as up-to-date.
> Another option is to use pg_clearxlogtail with gzip or use
> pglesslog. I haven't used pglesslog, but piping an empty WAL file
> through pg_clearxlogtail and gzip reduces it to about 16 kB (rather
> than 16 MB).
>
>> 2) Sometimes my slave does not read and delete WAL files when in
>> recovery mode. This will eventually fill up the disk.
>
> Sorry I can't help with that one -- we use our own scripts rather
> than pg_standby. Anyone else recognize this issue?
>
>> pg_controldata gives me:
>>
>> Minimum recovery ending location: 0/0
>>
>> What does that mean?
>
> I think that only has meaning when the cluster is in archive
> recovery status. What does pg_controldata say the "Database cluster
> state" is when you see this?
>
>> Is there any good ways of troubleshooting the behaviour, and
>> finding out precisely what state the slave is in, etc.?
>
> We use pg_controldata and check "Database cluster state" to ensure
> that our warm standbys are still "in archive recovery" and we check
> the "Time of latest checkpoint" to ensure that its age is not much
> beyond our archive_timeout setting -- to ensure that the data is
> indeed still flowing.
>
> I believe that 9.0 will be adding some nicer ways to check such
> things.
>
> -Kevin