Monitoring error logs in Oracle and Sql Server

In Oracle, there are 3 places that I know of that are important for monitoring: the bdump, where background process error is stored; udump, where user trace error is dumped; and cdump, the core dump, where Oracle internal error is dumped. cdump is in the binary format, you can use “strings -a” to look at things inside. All other trace and log files are text files that you can open up and read for yourself.

On Unix/Linux/Solaris based systems, these folders are located under:

$ORACLE_BASE/admin/$ORACLE_SID/bdump, udump, and cdump

To find out your $ORACLE_BASE and $ORACLE_SID, you can do:

echo $ORACLE_BASE and echo $ORACLE_SID

There is also the alert log, usually in the format of alert_$ORACLE_SID.log format, under the bdump folder.

There can be numerous trace and log files in these folders. To troubleshoot and correlate events with some problems, you can do:

ls -ltr

to sort files in ascending order according to date and time, and open up the file that is closest to the time when problem occurred. Those trace and log files may hold telltale signs of what you need to examine further.

For Sql Server, by default, the error log file is at C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG. And that is the only place you need to worry about. If you turn on certain trace, the trace info will also be logged into error log.

Don’t confuse Oracle’s .trc file with Sql Server’s .trc file. Oracle’s trace file is in text format, generated when certain trace flags are turned on. Sql Server’s trace file are in binary format, and can be read using Sql Server Profiler.

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