By default NV has the following datasets enabled:
QoS Class Map Statistics
QoS Police Color Statistics
QoS IP Hader compression Statistics
QoS Match Statistics
QoS Queueing Statistics
QoS Random Early Detect Statistics
QoS SET Statistics
QoS Traffic Shaping Statistics
Many people use QoS Class Map Statistics, few if any use the rest. The potential problem having them enabled is the unnecessary growth in the nms2.properties and nms2.pollinst tables to well over a million rows which could impact overall performance, as well as help bringing NV to the break point.
To see how many poll instances there are for these datasets go to the Console > File > License Info > check the box for 'Show details'. This will list all the datasets and their poll instances in the format of # / #, where the # on the left is the count for the enabled poll instances and the # on the right is the number of discovered poll instances.
All the discovered poll instances are additional rows in the nms2.pollinst table. In the case of the nnm2.properties table the number of rows added depends upon the dataset. In the case of the Device Availability dataset each poll instance adds two rows to the nms2.properties table. For the QoS Match Statistics dataset each discovered poll instance add 18 rows, and for QoS Queueing Statistics it is 23. It is easy to see how these unused poll instances will greatly add to the overall overhead NV has to work with.
To remove these poll instances go to the Console > Config > Polling > Datasets > select the dataset and change 'Poll Instance Expiration (days)' to 1, and click Set. In a distributed installation this has to be done at the MC and it will automatically get pushed down to the Pollers.
When discovery next runs the poll instances for the dataset will be set to Expiring and then get removed from the device and the database. Use the License Info Show Details to check the progress of the remove.
When all or most of the poll instances have been removed for the dataset go back to the dataset and uncheck the box for 'Polling Enabled' and Periodic discovery enabled' so they will both be disabled and then click Set.
When all done to optimize the database see:
Tech Tip - Database Optimization