Saving of configuration changes: Cache Dirty/Clean

Note: The CacheClean MIB variable is not displayed anywhere in Focal Point, the Web Interface, or the Command Line Interface (except via the “GET” and “GETNEXT” console commands).

When you make a configuration change to a Point System device, it is possible that the change will be lost or rejected some time after you have attempted to apply it. The CacheClean MIB variable for the device has a value of dirty(2) any time this is a possiblity.

When configuration changes are made, the Base Management Module immediately performs a validation of the request. But, since the Base Management Module is unable to detect all unnaceptable requests, a second validation must be performed by the device itself after the Base Management Module transfers the configuration to the device during their next conversation.

Between the time a change was requested by the user and the time the device confirms it, the application will appear to show that the change was accepted, whether or not the device considers it valid. This condition is known as a “dirty cache.”

Configuration requests will be lost or discarded under the following conditions:

  • The device is in hardware mode. Older CPSMM100 firmware only – newer firmware will reject the changes immediately with a genErrcode.
  • The configuration changes are illogical. For example, you tried to change the speed of a port when auto-negotiation is enabled. Where newer devices and current firmware are concerned, the Agent is frequently “smart” enough to detect these situations and immediately block them with a noSuchName error rather than depending upon the device to correct the error.
  • Either the Base Management Module or the device stop running for any reason before the changes have been accepted by the device. e.g. Power cycle, hot swap, reboot, reset, or crash.

When a device fails to accept some or all changes for one of the reasons above, the device ignores the change (if it ever saw it at all) and reports its actual configuration to the Base Mangement Module. As soon as the Base Management Module receives a validated configuration from the device, the cache becomes “clean” and the application will display the corrected configuration — which may not include your changes.

Each device that can be configured has a MIB variable called “devicenameCacheClean“.

CacheClean MIB variable
clean(1)Device and Management Module cache are synchronized, no automatic corrections to configuration will occur.
dirty(2)Device and Management Module cache are not synchronized. The configuration currently displayed by the application has not been validated by the device. The device may need to correct the configuration, in which case the displayed configuration will change.