Very frequent : Vacuuming child process timed out for db locking.tdb. Bottleneck?

[Nicolas Ecarnot]

Hi,

In our two-nodes ctdb setup, with an iscsi qdisk lun, the ctdb log files 
are showing frequent message such as :

Vacuuming child process timed out for db locking.tdb

Frequency is around every 3 minutes.

I read it may be due to too numerous locks to "balance/sync" between the 
nodes (did I read right?) and taking too much time.
This seems odd to me because we have around 300 users, doing basic 
office work, and not particular intensive activity. This seems classical 
to me.

Our iscsi network is dedicated, and not much loaded.

My two questions are :
- Could those error message mean this ctdb setup is LOOSING some locks, 
and thus two users may access read+write the same file (and then corrupt 
it)?
- what do you advice me to look at, or what to bench?

Thank you.

-- 
Nicolas Ecarnot