Finally I got around to providing a useful example for a cluster callout script. It is actually on the verge of taking too long-remember that scripts in the $GRID_HOME/racg/usrco/ directory should execute quickly. Before deploying this, you should definitely ensure that the script executes quickly enough-the “time” utility can help you with this. Nevertheless this has been necessary to work around a limitation of Grid Control: RAC One Node databases are not supported in GC 11.1 (I complained about that earlier).
To work around the problem I wrote a script which can alleviate one of the arising problems: when using srvctl relocate database, another instance (usually called dbName_2) will be started to allow existing sessions to survive the failover operation if they use TAF or FAN/FCF.
This poses a big problem to Grid Control though-the second instance didn’t exist when you registered the database as a target, hence GC doesn’t know about it. Subsequently you may get paged that the database is down when in reality it is not. Receiving one of the “false positive” alarms is annoying at best at 02:00 AM in the morning. Actually, Grid Control is right in assuming that the database is down: although detected as a cluster database target, it only consists of 1 instance. If that’s down, it has to be assumed that the whole cluster database is down. In a perfect world we wouldn’t have this problem-GC was aware that the RON database moved to another node in the cluster and update its configuration accordingly. This is planned for the next major release sometime later in 2011. Apparently dbconsole has the ability to deal with such a situation. Read the rest of this entry »