On 29/06/2015 11:38, Stéphane Schildknecht wrote:
On 16/06/2015 10:55, Xavier 12 wrote:
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@xxxxxxx:/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 ?
Thanks
Regards.
Xavier C.
I wonder why you are doing "cp" in your recovery.conf on the slave.
That is "quite" correct when the streaming can't get WAL from the master. But
cp is probably not the right tool.
You also cp from the master archive directory, and are cleaning on that
directory as well.
You don't clean up the standby xlog directory. And cp may copy incomplete WAL
files.
The streaming replication can take care of your xlog clean up, until you
introduce WAL files by another mean (manual cp for instance).
S.
cp because /var/lib/postgresq/9.1/wal_archive/ is a temporary directory.
I use it to build the replication (copy wal with rsync from the master).
The slave use it to start, then next wal are written ton
/var/lib/postgresql/9.1/main/pg_xlog.
Xavier C.
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