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I'm rather new to pg so please bear with me.

I've set up two hosts and installed pg10 on both. Then I configured log streaming replication between them. This worked fine.

I wanted to test fail over, so I stopped postgresql service on Primary and create trigger file on Standby, this also worked find. I check and my standby is not in recovery mode anymore.

Now I want to recover old Primary as new standby. I tried using pg_rewind but it gives me the following error message

/usr/lib/postgresql/10/bin/pg_rewind --target-pgdata=/var/lib/postgresql/10/main --source-server="host=server2ip port=5432 user=postgres"

target server needs to use either data checksums or "wal_log_hints = on"
Failure, exiting

I have wal_log_hints = on set on both servers.

Can anybody help me figure out how to get this to work.

Below are my settings which are the same on both servers. Replication before failing Primary worked great.

Below are lines which I changed in postgresql .conf

listen_addresses = '*'
max_connections = 200
tcp_keepalives_idle = 60
tcp_keepalives_interval = 10
tcp_keepalives_count = 5
wal_level = replica
wal_log_hints = on
archive_mode = on
archive_command = '/bin/true'
max_wal_senders = 5
wal_keep_segments = 5000
max_replication_slots = 5
effective_cache_size = 2GB

I also added the below lines to pg_hba.conf file

host    all             postgres        server1ip/24        trust
host    all             postgres        server2ip/24        trust

And finally I create recovery.conf file as below.

standby_mode          = 'on'
primary_conninfo      = 'host=sciontsdbbc01 port=5432 user=replicate password=rep-password'
trigger_file = '/tmp/PG_MasterNow'

1 Answer 1

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I have wal_log_hints = on set on both servers.

But presumably it was set too late, that is, after the generation of at least some of the WAL files involved in the rewind (in the pg_wal directory).

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  • indeed, I guess this will not do. I'll try to clone then repeat my fail-over exercise
    – Bart C
    Mar 28, 2019 at 11:37
  • did all my testing, works like a charm now, thanks a lot!!!
    – Bart C
    Mar 28, 2019 at 14:48

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