On 28/9/18 1:50 μ.μ., bhargav kamineni wrote:
Ee are using 9.5 version, slot option -s is not available ,can I go with -X stream option ?
-S is intended when you plan to use the backup as a hot standby, when you must use the same replication slot.
If you plan to use the backup as a stand alone backup you don't need this option anyway.
bhargav kamineni wrote:
> Hi Team,
>
> I have configured replication using slot ,But it failed by throwing the
> ERROR pg_basebackup: could not get transaction log end position from server:
> ERROR: requested WAL segment 0000000100002C9D00000085 has already been removed ,
> which is unexpected because i have created the slot on master first
> and then issued the base backup command from slave's end
> the command is
> usr/lib/postgresql/9.5/bin/pg_basebackup -U user --max-rate='150 M' --progress --verbose --write-recovery-conf --status-interval='10 s' -D data_dir -h host_ip -p 5433
> These are the settings on my master
> archive_mode=on
> archive_command='/bin/true'
> wal_keep_segments=512
> max_wal_senders=4
> Series of steps i have followed :
> 1) Enabled password less authentication between master and slave
> 2)created slot on master (assuming it will store wal's regardless of other settings)
> 3)started basebackup from slave's end
> 4)Issued checkpoint at master's end
>
> Here my concern is , slave should recover WAL from replication slot but why i
> got the above ERROR , Why slot removed the requested wal file , Could you please
> let me know the reason why it happened or did i miss something ?
I guess your base backup took long enough for the required WAL segments to be
removed by the time it was done.
To prevent that, create a replication slot *before* you perform pg_basebackup
and use the options "-S <slotname> -X stream" of pg_basebackup.
You then use the same slot in "recovery.conf".
That way you cannot lose any WAL.
Yours,
Laurenz Albe
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Cybertec | https://www.cybertec-postgresql.com
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Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt
