Re: [GENERAL] Interesting streaming replication issue - Mailing list pgsql-general
OK this is reproducible now.
- Stop a standby
- Write some data to the master
- Wait till the master has archived some WAL logs
- Wait till the archived logs have been removed from pg_xlog
- Start the standby.
The standby will recover all logs from the master log archive up to log X, it will then try to get log X+1 and fail (doesn't exist).
It will then try to start streaming log X (not X+1) from the master and fail (it's been archived). This will loop forever, example below.
scp: /archive/xlog//0000000D.history: No such file or directory2017-08-03 10:26:41 AEST [578]: [1037-1] user=,db=,client= (0:00000)LOG: restored log file "0000000C0000006 E000000AE" from archivescp: /archive/xlog//0000000C0000006E000000AF: No such file or directory2017-08-03 10:26:41 AEST [68161]: [1-1] user=,db=,client= (0:00000)LOG: started streaming WAL from primary at 6E/AE000000 on timeline 122017-08-03 10:26:41 AEST [68161]: [2-1] user=,db=,client= (0:XX000)FATAL: could not receive data from WAL s tream: ERROR: requested WAL segment 0000000C0000006E000000AE has already been removed
At this stage the standby has log X in pg_xlog, and this log has an identical md5 checksum to the log in the master archive.
Performing a pg_switch_xlog on the master pushes log X+1 to the archive, which is picked up by the standby allowing streaming replication to start.
The only interesting thing I can see in log X is that it's 99% made up of FPI_FOR_HINT records.
Any ideas?
Cheers,
James
James Sewell,
PostgreSQL Team Lead / Solutions Architect
Suite 112, Jones Bay Wharf, 26-32 Pirrama Road, Pyrmont NSW 2009
On Fri, Jul 28, 2017 at 6:28 AM, James Sewell <james.sewell@jirotech.com> wrote:
are you sure you're scp'ing from the archive, not from pg_xlog?Yes:restore_command = 'scp -o StrictHostKeyChecking=no 10.154.19.30:/archive/xlog//%f %p'Although you are right - that would almost make sense if I had done that!Sounds a lot like a cleanup process on your archive directory or something getting in the way. Are the logs pg is asking for in that archive dir?That's the strange thing - if you look at the log not only are they there, the standby has already retrieved them.It's then asking for the log again via the stream.--James Sewell,PostgreSQL Team Lead / Solutions ArchitectSuite 112, Jones Bay Wharf, 26-32 Pirrama Road, Pyrmont NSW 2009
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