Idle reservation recommendations

This page provides conceptual information on how Compute Engine generates idle reservation recommendations and on the parameters you can use to configure them.

Compute Engine provides idle reservation recommendations to help you identify on-demand reservations that have not been used over the previous 7 days. You can use idle reservation recommendations to find unused reservations, then modify or delete the reservations.

Compute Engine generates recommendations automatically based on system metrics gathered by the Cloud Monitoring service. You can configure idle reservations recommendations to receive more or fewer recommendations.

Pricing

There are no costs associated with using idle reservation recommendations. Using recommendations to reduce your resource usage can result in cost savings.

Limitations

Idle reservation recommendations are not available for the following reservations:

  • On-demand reservations that are attached to committed use discounts (CUDs)
  • On-demand reservations for virtual machine (VM) instances with TPUs

How detection of idle reservations works

Compute Engine generates recommendations about idle reservations based on historical usage metrics. By default, the historical observation period is 7 days. By changing the default observation period, you can customize the recommendations that you receive.

To generate recommendations, the algorithm considers reservations that accrue costs, but aren't associated with an active Compute Engine resource for the previous 7 days.

Frequency of recommendations

After a reservation is created and you haven't consumed any resources for at least 7 days, Compute Engine begins generating recommendations for it. New recommendations are generated once per day.

Customize recommendations

Compute Engine lets you customize the recommendations you receive for your project by changing the configuration used by the recommendation algorithm. In particular, by changing the default observation period, you can receive recommendations that better fit your workloads, applications, and infrastructure needs.

To learn how to modify the configuration for your project, see Configure idle reservation recommendations.

Choose the right configuration

This section describes the values that you can set for the configuration. Changing these values affects the recommendations that you receive.

The observation period

Set the observation period to modify the duration of the window used to calculate the recommendations.

You can set the observation period to a value between 7 days and 30 days, using a string with the total number of seconds, followed by the letter s.

  • For an observation period of 7 days, use "604800s".
  • For an observation period of 30 days, use "2592000s".

By default, the observation period is 7 days.

  • For recommendations based on short-term changes in your workload, use a shorter observation period.
  • For recommendations that are not affected by short-term fluctuations in your workload, use a longer observation period.

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