In MSP environment we quite often have requirements to store alarms in database for one or more months. This is not a problem in a perfect IT environment, but due to IT and UIM features the tables containing alarm history are growing quite quickly quite large and that makes then USM alarm portlet unable to use "Show Historical" feature. The code in USM seems to retrieve the whole history into browser and then do the filtering in context there. One solution for this could be some kind of documented way do delete selected alarms from alarm history tables. Now the only supported way is to DROP all those tables, meaning lose all the history and that is not always so suitable in MSP production env. We though could easily delete lots of alarms there, an example: Informational alarms from interface_traffic probe sending 10s of alarms per cycle telling that some ports are having operational status: down.