BigBrother is based on a simply concept:
- one server, which collects all data sent by
- the clients, which run on every to-be monitored server.
The client agents not only report good/failure, but also send other (related) status information, possibly long reports about your servers health.
While this is a good concept, the original BigBrother implementation is crap. And they even charge you a lot for this bunch of unholy shell scripts. Avoid it.
BigSister is a complete rewrite of the BigBrother system (which you aren't allowed to modify anyway). BS is written in OO-perl and has a clean concept of doing its stuff. It is also highly configurable and compatible with the BigBrother clients. So you can slowly migrate from a BB-based monitoring system to BS. Just upgrade the server/collector and your dreams become true (or at least sort of :).
(Most of this applies to BB as well.) Install the agents into some folder in /opt, probably /opt/monitoring/bsc. Have the clients run as a special user (maybe bs, or bb if you upgrade from BB), and have them write their status stuff into $BSHOME/tmp or $BSHOME/var. Don't forget to monitor the disk space for $BSHOME - else your agents may hang (and report ok while something goes wrong).
It's advisable to send copies of the alerts to a special log email address, so you have an easily searchable source for previous alerts.