what is monetdb doing?

Hi all,

I've run into a behaviour that I would like to understand and possibly disable. Two times per day the mserver daeomon starts trashing the disk furiously, I see that the size on disk of data directory goes up to 115 GB from 85 GB and then comes back again to the same initial size, during this process disk utilization goes trough the roof. Can anyone tell me what is monetdb doing? There are no import/export process running at this times, it seems that monetdb is doing some kind of data compaction... is there anyway to disable this?

$ mserver5 --version MonetDB 5 server v11.15.7 "Feb2013-SP2" (64-bit, 64-bit oids)

Thanks!