Hello, Omar. This error took some research. In every case that this error is seen by our phone techs, the RAID controller is replaced.  After talking to some senior engineers, I'd recommend replacing that controller.  This error can occur from either, improperly shutting down the array leading to a corruption of the backup meta-database, or the cache stick (a little SD card) could come unseated. You *could* try removing the controller, wait for the 'flee power' to drain, reseat that cache card, and then put it back in the slot. That may clear that error, but no promises. However, we don't replace the cache cards in these. The only thing we do replace inside the controller is the battery.  I hope that helps you out. Let me know if you have any questions. 
Hello All, I appreciate your time and assistance with the following question. I recently upgraded to the latest firmware on my PV MD3220i and installed the corresponding NVRAM update. After installing the update, I am getting the following error in the MDSM.  I checked the cache backup capacity and the total used are both reporting 1680MB. Is there a reason that the error is occurring and what is the best approach to fixing this issue? I checked the forums but didn't see anything specific besides replacing the module or upgrading the actual cache memory.  Otherwise, the unit is working without issue but just like most of you, I hate that blinking amber light in a perfectly blue data-center :)  Thanks!Omar
PowerVault MD3220i Error (Insufficient Cache Backup Device Capacity)