Using statistics level 1 is adequate for monitoring performance. In some instances you might need to collect more performance statistics, for example, to troubleshoot performance problems.

Before you increase the statistics level for an interval, view charts in real time. Viewing real-time data has less impact on performance because metrics are retrieved directly from the source without being written to the vCenter Server database.

If you change to statistics level 3 or 4 to diagnose problems, reset the statistics level to its previous state as soon as possible. At statistics level 4, limit the collection period to the Day interval to not have an impact on the database. To save the data for longer than one day, increase the interval to two or three days rather than using the Week interval. For example, to record data over the weekend, set the interval to three days. Use a week interval only when you need the duration to be more than three days.

Collection Level Scenarios lists the circumstances in which you might want to increase the statistics level for your vCenter Server.

Collection Level Scenarios

Use Collection Level

To do this


Identify virtual machines that can be co-located because of complimentary memory sharing.

Detect the amount of active memory on a host to determine whether it can handle additional virtual machines.


Compare ready and wait times of virtual CPUs to determine the effectiveness of VSMP.

Diagnose problems with devices, or compare performance among multiple devices.


Determine whether a device is being saturated.

Troubleshoot errors.