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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Checking that the instance is up
Hi Peter,
I remember the thread, but couldn't remember the subject line at all..
Having had this discussion countless times in the past, here's what I would opt for:
The best way to make sure that an instance is alive and running would be to do a full connection to that instance, and run a simple piece of sql - such as "select 'PING' from dual;". This makes sure that both the listener, and instance are both up and readily accepting connections.
You can also monitor for the listener status separately, based upon a "TNSPING <SID>" command, that will alert simply to the status of the listener.
We do both of these with our monitoring tool, and generate ENTITY_DOWN and NETWORK_DOWN alerts respectively. If you get both an ENTITY_DOWN and NETWORK_DOWN error message at the same time, then this helps to point you at the listener quicker than trying to diagnose why the instance is down. If you just get an ENTITY_DOWN message on it's own, then it points to a database based problem.
You should also try and catch the error messages on a failure, and flag those in your warning messages.
And of course, there is the point of monitoring the monitor. You should have some process in place that is making sure that the monitor is up and running correctly. Whether this be a date/timestamp placed in to a log file with every successful "ping", or making sure a cron/AT job is running etc. depends on how you do this..
Of course, you could buy a tool that already does all of this.. ;)
HTH Mark
-----Original Message-----
Robson, Peter
Sent: 18 December 2003 13:59
To: Multiple recipients of list ORACLE-L
Folks -
Some months ago there were exchanges on the optimum way to check that an instance was alive.
I have searched, hunted and generally scavenged for these exchanges, but without luck.
Can anyone give me the subject line, and I can turn again to the archive?
thanks,
peter
edinburgh
BGS. . http://www.bgs.ac.uk *********************************************************************
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