antirez/redis — Issue #368: Redis slowing down when rewriting AOF files
Author: ehudros
Created: 2012-03-01 14:13:20+00:00
State: open

We're running Redis on an EC2 instance (on an EBS device).
Every time Redis tries to re-write the AOF file it ends up slowing down to an almost complete halt.

This is the log output I currently have:
[2314] 01 Mar 05:50:23 * Starting automatic rewriting of AOF on 100% growth
[2314] 01 Mar 05:50:23 * Background append only file rewriting started by pid 19350
[2314] 01 Mar 05:50:27 * Asynchronous AOF fsync is taking too long (disk is busy?). Writing the AOF buffer without waiting for fsync to complete, this may slow down Redis.
[2314] 01 Mar 05:50:43 * Asynchronous AOF fsync is taking too long (disk is busy?). Writing the AOF buffer without waiting for fsync to complete, this may slow down Redis.
[19350] 01 Mar 05:51:45 * SYNC append only file rewrite performed
[2314] 01 Mar 05:51:45 * Background AOF rewrite terminated with success
[2314] 01 Mar 05:51:45 * Parent diff successfully flushed to the rewritten AOF (882173 bytes)
[2314] 01 Mar 05:51:45 * Background AOF rewrite successful
[2314] 01 Mar 05:51:49 * Asynchronous AOF fsync is taking too long (disk is busy?). Writing the AOF buffer without waiting for fsync to complete, this may slow down Redis.

Is this normal behavior? Is there any way to work around the issue?
Thanks!