Auto Compaction seems to run even when turned off

Doing some testing, I turned off autocompaction by simply unchecking the threshold boxes in the global auto-compaction setting. The bucket was not set to override.

Under constant update load, I would have expected the disk utilization to grow constantly.

However, I observed that it would grow to a point, and then shrink back down and repeat. This is similar to what we would observe when compaction is turned on. However, turning compaction on produces even more dramatic swings in disk usage so I believe there is some "rogue" compaction process running even when it should be turned off.

The logs show sometimes it skips the compaction, and then sometimes it does it:
[ns_server:info,2013-10-01T10:12:55.940,ns_1@10.196.6.253:<0.32626.4>:compaction_daemon:try_to_cleanup_indexes:650]Cleaning up indexes for bucket `beer-sample`
[ns_server:info,2013-10-01T10:12:55.944,ns_1@10.196.6.253:<0.32626.4>:compaction_daemon:spawn_bucket_compactor:609]Compacting bucket beer-sample with config:
[

{parallel_db_and_view_compaction,false},
{database_fragmentation_threshold,{undefined,undefined}},
{view_fragmentation_threshold,{undefined,undefined}}]
[ns_server:info,2013-10-01T10:13:17.519,ns_1@10.196.6.253:ns_config_rep<0.509.0>:ns_config_rep:do_pull:341]Pulling config from: 'ns_1@10.196.0.103'

[ns_server:info,2013-10-01T10:13:25.959,ns_1@10.196.6.253:<0.81.5>:compaction_daemon:try_to_cleanup_indexes:650]Cleaning up indexes for bucket `beer-sample`
[ns_server:info,2013-10-01T10:13:25.965,ns_1@10.196.6.253:<0.81.5>:compaction_daemon:spawn_bucket_compactor:609]Compacting bucket beer-sample with config:
[{parallel_db_and_view_compaction,false}

,
{database_fragmentation_threshold,{undefined,undefined}},
{view_fragmentation_threshold,{undefined,undefined}}]
[ns_server:info,2013-10-01T10:13:25.969,ns_1@10.196.6.253:<0.84.5>:compaction_daemon:spawn_dbs_compactor:755]Compacting databases for bucket beer-sample
[ns_server:info,2013-10-01T10:13:25.974,ns_1@10.196.6.253:<0.86.5>:compaction_daemon:spawn_vbucket_compactor:904]Compacting <<"beer-sample/171">>
...
...

Logs are at: http://s3.amazonaws.com/customers.couchbase.com/perry/compaction2013_10_01.zip