I just discovered that the /opt/zimbra/zmstat/zmstat.out* log files are really huge (in fact no so huge after compression by gzip).

They all (ie every day since at least one week, no logs before) contain about 2.4 millions lines with exactly the same error:
"Use of uninitialized value in subtraction (-) at /opt/zimbra/libexec/zmstat-allprocs line 118."

It seems that this line is logged around 28 times every second.

Stopping and restarting stats (with zmstatctl stop ; zmstatctl start) doesnt seem to stop (at least after some minutes) such logging.

The log file seems to be updated every 30s (but not sure if this is not just an effect of linux write buffering)

I am using ZCS 6.04 on ubuntu 8.04