When looking at a computer's Resource Change History (right click on computer > CMDB Functions > Resource Change History), it is noticed that certain changes that were made are not being recorded, or, older changes that were previously there have been removed. For example, the computer's Status was recently changed to Retired, but no reference to this is found.
Resource History has been configured to remove certain historical changes, and/or in SQL, history tables have been emptied or reduced in record count. When these occur, the Resource Change History either will not record certain changes any longer or older changes are removed.
Ensure that Resource History is not set to disable recording changes or is limiting the retention of the changes to a short date range.
In a Symantec Management Console, click on the Settings button > Notification Server > Purging Maintenance.
Click on Resource History.
Click on the Resource Association History tab.
Click on to expand the areas here, checking to ensure that any desired items are enabled and that their retention is at an appropriate date range. Most items are enabled and set to 12 months by default. For example, click on and expand Resource Associations. If Asset's Status is unchecked, changes to the Status are not recorded in Resource Change History or in the ResourceAssociationHistoryDelta table. If this is set to 1 day, then any changes made will no longer appear in Resource Change History after the 2nd day. Note: Disabling any items or setting their retention date range does not affect the actual data, only their historical references. For example, viewing a computer will still show its Status that its been set to even if its history has been disabled or removed by Resource History.
In SQL, to avoid the loss of data for Resource Change History, it is recommended to not truncate or remove records from historical tables. However, in some cases this is required due to their extreme size to resolve performance issues. For more information abut this, refer to the following article (which is internal, please contact Symantec Technical Support to obtain a copy of this):
Can history tables be emptied to improve server performance or timeouts? HOWTO83316
Note: Once historical data has been deleted, regardless of the cause, it cannot be recovered short of restoring the database to a point where this data used to exist at.