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.