A false alarm or no alarm is triggered when an Oracle tablespace runs out of space.
The rule "DBO - Tablespace Used Percentage" may not fire.
Investigating Oracle tablespace alarm issues.
CAUSE 1:
For tablespaces with autoextensible tablespaces, OS monitoring is required for the DBO Tablespace Usage to be accurately calculated.
If Foglight cannot collect the OS data for an autoextendable tablespace, the alert will not function because it does not have enough information to calculate to result.
CAUSE 2:
The parameter "Is ASM RAC" has been changed from "True" to "False" via "Administration | Agents | Agent Status". This causes duplicate topology objects and the needed table space metric will not be submitted to the correct "new" topology object. The rule is still reading from the old topology object which is empty now.
TO TROUBLESHOOT ORACLE TABLESPACE ALARM ISSUES
Check the collection parameters from the Error in the Agent log to confirm that the collection ran
Check that the ASM agent and OS collection are both running (when the datafile is autoextensible on the disk or ASM)
Check the datafile number in the database using SELECT COUNT(*) FROM DBA_DATA_FILES;
Check the max row limit in the collection (this can cause some datafile information to not be retrieved from the database)
Set the FglAM or database agent to enable debug log writing to check the results for the "DBO - Tablespace free space ASM" with the result from SELECT * FROM DBA_DATA_FILES; to ensure that all datafiles are included in the calculation.
RESOLUTION 1:
Turn off the autoextend capability on the Oracle tablespace or configure and activate OS monitoring (IC agent and Oracle agent) for the Oracle instance.
RESOLUTION 2:
Drop the agent and recreate it with the correct settings.
Please Note
The DBO cartridge is querying ASM views that resides on monitored instance to retrieve basic information about ASM I/O activity, however the data is not always reported correctly due to multiple Oracle ASM related bugs.
The following are the Oracle ASM known bugs:
RESOLUTION 3:
By default the normal sensitivity template has the warning condition of the tablespace rule disabled. To enable it follow the steps below:
Note:
If a condition is not configured in the rule itself, you can enable it in the sensitivity level template, but it has not affect and no alarm will be triggered.
Find more details about sensitivity levels in this blog post.
RESOLUTION 4
Please refer to KB 4281739 for additional resolutions for this issue.
RESOLUTION 5
The calculation is correct but due to the size of the DB the thresholds needs to be adjusted because it is based on percentage and not on numbers. When having 4 TB free space, 10% remaining free space is a high number, but as the rule is based on percentage an alarm will be triggered even there is still a lot of space available.
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