Rollup is the process by which CES calculates the average, maximum, minimum, and variance values based on sample raw data collected in different periods. The calculation period is called a rollup period.

Rollup is a smooth calculation process. The longer the rollup interval, the more smoothly processing will be implemented, and the more accurate the generated data for trend prediction and statistics will be. The shorter the rollup interval is, the more accurate the generated data for alarm reporting will be.

The rollup period can be 5 minutes, 20 minutes, 1 hour, 4 hours, and 1 day.

The methods CES uses to process collected data vary depending on the data type:

• If the data is an integer, the data will be rounded.
• If the data is a decimal fraction, two decimal places will be retained. Any further decimal places will be rounded.

For example, the instance quantity in AS is an integer. If the rollup period is 5 minutes, the values of collected metric data are 1 and 4, then the average value is 2 instead of 2.5.

You can choose the CES mode based on the characteristics of the rollup to meet your service requirements.