Re: Trouble with replication

From: pgsql-general-owner(at)postgresql(dot)org [pgsql-general-owner(at)postgresql(dot)org] on behalf of John R Pierce [pierce(at)hogranch(dot)com]
Sent: Wednesday, June 05, 2013 5:00 PM
To: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] Trouble with replication

On 6/5/2013 1:39 PM, David Greco wrote:
I’ve setup two 9.2.4 servers to serve as master-slave in a streaming replication scenario. I started with a fresh database on the master, setup the replication, then imported using pg_restore about 30GB of data. The master and slave are geographically separated, so replication of this amount of data can/should take hours. I saw from pg_last_xlog_receive_location and pg_last_xlog_replay_location that the slave began to receive the replication information, it eventually quit with the following errors in the log:

2013-06-05 16:28:43.198 EDT,,,19978,,51af9f7a.4e0a,2,,2013-06-05 16:28:42 EDT,,0,FATAL,XX000,"could not receive data from WAL stream: FATAL: requested WAL segment 000000010000000000000022 has already been removed
",,,,,,,,,""

I suspect you'll need to set the parameter that controls how many WAL log files are kept on the server high enough to cover this replication catchup period.

geographically separated high latency connections are very problematic for any sort of replication.

On the master or on the slave, or on both? I thought shipping the archived WAL files from the master to the slave did this already?