eG Monitoring
 

Measures reported by OraDumpAreaTest

Trace files, typically used for troubleshooting issues with key database operations, are stored in dump area destinations marked for every such operation. For instance, a background dump destination can be specified using the BACKGROUND_DUMP_DEST initialization parameter in Oracle; trace files for the background processes are written to this destination only. Similarly, trace files for user processes are generated and stored in the user dump destination, which is set using the USER_DUMP_DEST parameter in Oracle.

The dump destinations so created should be adequately sized, so that there is always enough space in the destination directory for storing trace files. If any of the destination directories become full, then trace files cannot be created for the corresponding database operation; while the absence of trace files can make debugging difficult, in some cases, it can even bring the database operations to a standstill.

In order to avoid such anomalies, the usage of each dump destination should be monitored, and administrators promptly alerted to space inadequacies, so that required space is made available in the dump directory. The OraDumpArea test serves this purpose effectively. This test runs periodic checks on the usage of every dump destination that has been configured for monitoring, and alerts administrators if any of the configured dump destinations or dump drives are likely to run out of space.

Note:

For this test to work, the eG install user should be in the Oracle User Group.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Dump_area_used Indicates the amount of space in this dump destination that is currently occupied by trace files. MB  
Total_used_area Indicates the space in the dump drive that is currently occupied by all files, including trace files. MB  
Pct_dump_area_used Indicates the percentage of the total used space in the dump drive that is occupied by trace files. Percent This measurement value should ideally be below 50%. Any value higher than 50%, indicates that the trace files are consuming more space than the other files in the dump drive. To free some space in that drive, you can adopt any of the following approaches:
  • Add more disk space to the dump drive;
  • Take backups of the old trace files to tape or to another destination, and remove them from the dump directory;
  • Temporarily, you can even zip all trace files in the dump destination.

If sufficient space is not made available to the dump destination soon, then trace files can no longer be created in the directory; sometimes, this can cause the Oracle instance to fail.
Available Indicates the available free space in the dump drive. MB  
Pct_available Indicates the percentage of space in the dump drive that is currently unused. Percent This measurement value should ideally be high. If the value is consistently low, you may want to check the value of the Pct_dump_area_used measure to determine what is causing the space drain - is it because of the trace files, or the other files in the dump destination drive? If the trace files appear to be consuming excessive space in the drive, you can free some space in the drive by adopting any of the following approaches:
  • Add more disk space to the dump drive;
  • Take backups of the old trace files to tape or to another destination, and remove them from the dump directory;
  • Temporarily, you can even zip all trace files in the dump destination.
Dump_growth Indicates the rate at which the dump files occupy space in the dump drive during the last measurement period. MB/sec Ideally the value of this measure should be low. A high value indicates that there exists a space constraint in the dump drive and reveals that the I/O related activity is high in the drive.