initial sync of multiple streaming slaves simultaneously - Mailing list pgsql-general

From Mike Roest
Subject initial sync of multiple streaming slaves simultaneously
Date
Msg-id CAE7Byhh+Mzet_D4ROCeFBMdnoO69_0sbZ6FNq1KZH4cCB1dJvw@mail.gmail.com
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Responses Re: initial sync of multiple streaming slaves simultaneously
Re: initial sync of multiple streaming slaves simultaneously
List pgsql-general
Hey Everyone,
    We currently have a 9.1.5 postgres cluster running using streaming replication.  We have 3 nodes right now

2 - local that are setup with pacemaker for a HA master/slave set failover cluster
1 - remote as a DR.

Currently we're syncing with the pretty standard routine

clear local datadir
pg_start_backup
sync datadir with fast-archiver (https://github.com/replicon/fast-archiver)
pg_stop_backup 
start slave

We use the streaming replication with wal_keep_segments set to 1000 to get the required WAL files to the slaves.

With this procedure we can currently only sync one of the slaves at a time if we failover.  As when the second machine goes to start the sync it errors out cause trying to run pg_start_backup fails.

We're looking into was to allow both the slave and the DR to sync at the same time.

The procedure I'm currently testing is 

clear localdatadir
pg_start_backup
scp datadir/backuplabel
pg_stop_backup
sync datadir with fast-archiver
start slave

This seems to be working and the slave comes up correctly and streams the WAL files it needs from the backup_label that was copied during the pg_start_backup/pg_stop_backup

Is there any hidden issue with this that we haven't seen.  Or does anyone have suggestions as to an alternate procedure that will allow 2 slaves to sync concurrently.


Thanks

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