Cloud volume policies

Aggressiveness

Turbonomic uses Aggressiveness when evaluating IOPS and throughput.

When evaluating performance, Turbonomic considers resource utilization as a percentage of capacity. The utilization drives actions to scale the available capacity either up or down. To measure utilization, the analysis considers a given utilization percentile. For example, assume a 95th percentile. The percentile utilization is the highest value that 95% of the observed samples fall below. Compare that to average utilization, which is the average of all the observed samples.

Using a percentile, Turbonomic can recommend more relevant actions. This is important in the cloud, so that analysis can better exploit the elasticity of the cloud. For scheduled policies, the more relevant actions will tend to remain viable when their execution is put off to a later time.

For example, consider decisions to reduce capacity. Without using a percentile, Turbonomic never scales below the recognized peak utilization. Assume utilization peaked at 100% just once. Without the benefit of a percentile, Turbonomic will not reduce resources for that volume.

With Aggressiveness, instead of using the single highest utilization value, Turbonomic uses the percentile you set. For the previous example, assume a single burst to 100%, but for 95% of the samples, utilization never exceeded 50%. If you set Aggressiveness to 95th Percentile, then Turbonomic can see this as an opportunity to reduce resource allocation.

In summary, a percentile evaluates the sustained resource utilization, and ignores bursts that occurred for a small portion of the samples. You can think of this as aggressiveness of resizing, as follows:

• 99th or 100th Percentile – More performance. Recommended for critical volumes that need maximum guaranteed performance at all times, or those that need to tolerate sudden and previously unseen spikes in utilization, even though sustained utilization is low.

• 95th Percentile (Default) – The recommended setting to achieve maximum performance and savings. This assures performance while avoiding reactive peak sizing due to transient spikes, thus allowing you to take advantage of the elastic ability of the cloud.

• 90th Percentile – More efficiency. Recommended for volumes that can stand higher resource utilization.

By default, Turbonomic uses samples from the last 30 days. Use the Max Observation Period setting to adjust the number of days.

Max Observation Period

To refine the calculation of resource utilization percentiles, you can set the sample time to consider. Turbonomic uses historical data from up to the number of days that you specify as a sample period. If the volume has fewer days' data then it uses all of the stored historical data.

Choose from the following settings:

• Less Elastic – Last 90 Days

• Recommended – Last 30 Days

• More Elastic – Last 7 Days

Min Observation Period

This setting ensures historical data for a minimum number of days before Turbonomic will generate an action based on the percentile set in Aggressiveness. This ensures a minimum set of data points before it generates the action.

Especially for scheduled actions, it is important that resize calculations use enough historical data to generate actions that will remain viable even during a scheduled maintenance window. A maintenance window is usually set for "down" time, when utilization is low. If analysis uses enough historical data for an action, then the action is more likely to remain viable during the maintenance window.

Choose from the following settings:

• More Elastic – None

• Less Elastic – 1, 3, or 7 Days