onstat -o Output Shared Memory
The onstat -o command dumps the contents of shared memory out to the specified file for later analysis. The command has two command options for controlling the output. The filename to be created can be passed via the command line, the default is onstat.out
nobuffs option excludes the buffer pool in the resident segment of shared memory from the output file. This results in a smaller output file.
full option creates an output file that is the same size as the shared memory segments for the instance. You must have enough room in the file system to handle the output
If you do not specify either the nobuffs or the full option, the output is controlled by the database server DUMPSHMEM configuration parameter setting:
If DUMPSHMEM is set to 0 or to 1, onstat -o command writes a full shared-memory dump file.
If DUMPSHMEM is set to 2, onstat -o command writes a nobuffs shared-memory dump file that excludes the buffer pool in the resident segment.
The file created by the onstat -o command can be the same size as the shared memory segments for the
instance. Be sure you have enough room in the file system to handle the output.
If no file name is provided, onstat -o will place its output into a file called onstat.out.
Monitoring and Tuning
The onstat -o command allows you to capture the current shared memory information to a flat file.
By executing additional onstat commands against the file, it is possible to acquire information from a
previously saved shared memory dump.