Re: PITR - warm standby switchover question

Well, if you don't delete the recovery.conf and you *do* delete
pg_standby's stop file (or it gets deleted, for example if you set it
to go under /tmp and the server is restarted for whatever reason) the
server will attempt to go back into recovery mode using your
configured recovery command in the recovery.conf.  I'm not sure
exactly what would happen if the stop file is still there but I would
expect pg_standby to kick in due to the recovery.conf, see the stop
file, and let the server finish starting up.  However, I haven't
really tested that before and I certainly wouldn't call it "clean".
The best option would probably be to write a small script to drop the
stop file, wait until it can get a valid connection to the db, the rm
the stop file and mv the recovery.conf to something like
recovery.conf.inactive or something along those lines.

On Apr 14, 2009, at 5:23 PM, Dan Hayes wrote:

> Excellent!  Thanks.  One other quick question...  What would happen
> if I didn't delete the recovery.conf file?  Is that step just to
> prevent accidentally restarting the server with it there?
>
> On Tue, Apr 14, 2009 at 6:26 PM, Erik Jones <ejones@engineyard.com>
> wrote:
>
> On Apr 14, 2009, at 3:47 PM, Dan Hayes wrote:
>
> I've followed the implementation instructions at 24.4.2:
> http://www.postgresql.org/docs/current/static/warm-standby.html
>
> And I've used the archive/restore commands from the example in F23.2:
> http://www.postgresql.org/docs/current/static/pgstandby.html
>
> This all works great.  The primary backs up the WAL archives to a
> mutually accessible folder and the backup system is continuously
> reading in the logs.  Monitoring the "standby.log" file shows that
> the system is working as it should.
>
> My question is, if the main system goes down, what do I do to the
> backup machine to make it come alive?  Currently, when I attempt to
> login to the database, I get the error: "psql: FATAL:  the database
> is starting up"  I'm assuming this means it can't be accessed while
> its in continuous recovery mode.  I attempted to turn off postgresql
> on the main server and try connecting again, same error (was
> obvious, but I do things one step at a time...)  So then I removed
> the "recovery.conf" file on the backup server and attempted to
> restart postgresql.  It stopped fine, but the restart failed.
>
> The pg_log/postgresql-XXXX-XX-XX.log file says:
> LOG:  database system was interrupted while in recovery at log time
> 2009-04-14 17:36:14 CDT
> HINT:  If this has occurred more than once some data might be
> corrupted and you might need to choose an earlier recovery target.
> LOG:  could not open file "pg_xlog/0000000100000002000000DD" (log
> file 2, segment 221): No such file or directory
> LOG:  invalid primary checkpoint record
> LOG:  could not open file "pg_xlog/0000000100000002000000DC" (log
> file 2, segment 220): No such file or directory
> LOG:  invalid secondary checkpoint record
> PANIC:  could not locate a valid checkpoint record
> LOG:  startup process (PID 3756) was terminated by signal 6: Aborted
> LOG:  aborting startup due to startup process failure
>
> Any ideas what I'm doing wrong?  How do I bring the standby server
> out of standby do act as the primary?
>
> You should use pg_standby's -t flag to specify a stop file.  Then
> all you need to do is touch (create) that file and pg_standby will
> let the server come out of recovery mode into normal operation
> mode.  Be sure to rm or mv the recovery.conf once that is complete.
>
> Erik Jones, Database Administrator
> Engine Yard
> Support, Scalability, Reliability
> 866.518.9273 x 260
> Location: US/Pacific
> IRC: mage2k
>
>
>
>
>
>

Erik Jones, Database Administrator
Engine Yard
Support, Scalability, Reliability
866.518.9273 x 260
Location: US/Pacific
IRC: mage2k