Re: pg_xlog on a hot_stanby slave

On 16/06/2015 22:28, Guillaume Lelarge wrote:
> 2015-06-16 15:55 GMT+02:00 Xavier 12 <maniatux(at)gmail(dot)com
> <mailto:maniatux(at)gmail(dot)com>>:
>
> I don't think so. There is no archive_command and the master doesn't
> ship its wal here.
> But how can I check that ?
>
>
> What's the complete path to the directory on the salve that contains
> 951 files? what does PostgreSQL say on its log files?

in /var/lib/postgresql/9.1/main/pg_xlog/

1059 files today.
Too much to copy/paste here.
Here are the first ones :

-rw------- 1 postgres postgres 16777216 Jun 9 08:40
000000040000040B0000007E
-rw------- 1 postgres postgres 16777216 Jun 9 08:41
000000040000040B0000007F
-rw------- 1 postgres postgres 16777216 Jun 9 08:42
000000040000040B00000080
-rw------- 1 postgres postgres 16777216 Jun 9 08:44
000000040000040B00000081

There are no .done or .ready and archive_status is empty.

Nothing critical in the logs :

Jun 17 08:55:11 psql02 postgres[4231]: [2-1] 2015-06-17 08:55:11 CEST
LOG: paquet de d?marrage incomplet
Jun 17 08:55:41 psql02 postgres[4322]: [2-1] 2015-06-17 08:55:41 CEST
LOG: paquet de d?marrage incomplet
Jun 17 08:56:11 psql02 postgres[4356]: [2-1] 2015-06-17 08:56:11 CEST
LOG: paquet de d?marrage incomplet
Jun 17 08:56:41 psql02postgres[4460]: [2-1] 2015-06-17 08:56:41 CEST
LOG: paquet de d?marrage incomplet
Jun 17 08:56:55 psql02postgres[4514]: [2-1] 2015-06-17 08:56:55 CEST
ERREUR: restauration en cours
Jun 17 08:56:55 psql02postgres[4514]: [2-2] 2015-06-17 08:56:55 CEST
ASTUCE : les fonctions de contr?le des journaux de transactions ne
peuvent pas
Jun 17 08:56:55 psql02postgres[4514]: [2-3] #011?tre ex?cut?es lors de
la restauration.
Jun 17 08:56:55 psql02postgres[4514]: [2-4] 2015-06-17 08:56:55 CEST
INSTRUCTION : select pg_current_xlog_location()

pg_current_xlog_location() is for a zabbix check, "ERREUR" is because
that server is readyonly.

Xavier C.

>
> 2015-06-16 12:41 GMT+02:00 Guillaume Lelarge
> <guillaume(at)lelarge(dot)info <mailto:guillaume(at)lelarge(dot)info>>:
> > Le 16 juin 2015 10:57 AM, "Xavier 12" <maniatux(at)gmail(dot)com
> <mailto:maniatux(at)gmail(dot)com>> a écrit :
> >>
> >> Hi everyone,
> >>
> >> Questions about pg_xlogs again...
> >> I have two Postgresql 9.1 servers in a master/slave stream
> replication
> >> (hot_standby).
> >>
> >> Psql01 (master) is backuped with Barman and pg_xlogs is correctly
> >> purged (archive_command is used).
> >>
> >> Hower, Psql02 (slave) has a huge pg_xlog (951 files, 15G for 7 days
> >> only, it keeps growing up until disk space is full). I have found
> >> documentation and tutorials, mailing list, but I don't know what is
> >> suitable for a Slave. Leads I've found :
> >>
> >> - checkpoints
> >> - archive_command
> >> - archive_cleanup
> >>
> >> Master postgresq.conf :
> >>
> >> [...]
> >> wal_level = 'hot_standby'
> >> archive_mode = on
> >> archive_command = 'rsync -az
> /var/lib/postgresql/9.1/main/pg_xlog/%f
> >> barman(at)nas(dot)lan:/data/pgbarman/psql01/incoming/%f'
> >> max_wal_senders = 5
> >> wal_keep_segments = 64
> >> autovacuum = on
> >>
> >> Slave postgresql.conf :
> >>
> >> [...]
> >> wal_level = minimal
> >> wal_keep_segments = 32
> >> hot_standby = on
> >>
> >> Slave recovery.conf :
> >>
> >> standby_mode = 'on'
> >> primary_conninfo = 'host=10.0.0.1 port=5400 user=postgres'
> >> trigger_file = '/var/lib/postgresql/9.1/triggersql'
> >> restore_command='cp /var/lib/postgresql/9.1/wal_archive/%f "%p"'
> >> archive_cleanup_command =
> >> '/usr/lib/postgresql/9.1/bin/pg_archivecleanup
> >> /var/lib/postgresql/9.1/wal_archive/ %r'
> >>
> >>
> >>
> >>
> >>
> >> How can I reduce the number of WAL files on the hot_stanby slave ?
> >>
> >
> > Depends on what you're talking about. If they are archived wal,
> > pg_archive_cleanup is what you're looking for.
>
>
>
>
> --
> Guillaume.
> http://blog.guillaume.lelarge.info
> http://www.dalibo.com