Node group autoscaler

This page provides an overview of the node group autoscaler. For instructions on how to use the node group autoscaler, read Autoscaling node groups.

The node group autoscaler can help you automatically manage the sizes of your sole-tenant node groups by:

  • Increasing the size of a node group when there is insufficient capacity for another virtual machine (VM) instance on that node group. After the autoscaler increases the size of the node group, the VMs are scheduled transparently.

  • Decreasing the size of a node group when there are empty nodes, which prevents you from paying for unused sole-tenant nodes.

Autoscaler modes

By default, the autoscaler is not enabled on node groups. When the autoscaler is not enabled, you must manually manage the sizes of your node groups. If you enable the autoscaler on a node group, you can specify that the autoscaler both increases and decreases the size of the node group (scales out and scales in), or that it only increases the size of the group (only scales out).

Scale out and scale in

In this mode, the node group autoscaler both increases (scales out) and decreases (scales in) the size of your node groups. For this mode, you must specify a maximum size and a minimum size for the node group. The autoscaler will not scale the size of the node group above the specified maximum or below the specified minimum.

The autoscaler scales out the size of a node group when there is a request to schedule a VM onto a node group that does not have capacity for another VM. Conversely, the autoscaler scales in the size of a node group when there is an empty node in the node group.

Only scale out

With this mode, the autoscaler increases the size of the node group in response to requests to schedule VMs, but doesn't remove empty nodes from node groups. Google recommends this mode for monotonically increasing workloads or workloads that require physical server affinity, such as BYOL workloads, which require licenses to reside on the same physical server.

You must use this mode if your node groups are configured to restart their hosted VMs on minimal servers.

Size range of a node group

When you enable the autoscaler, you set the size range of the node group by specifying a minimum and maximum value for the node group size.

If you do not specify a value for the minimum size, the autoscaler sets the minimum size to zero (0). If you do a specify value for the minimum size, it must be an integer greater than equal to 0, and it must be less than or equal to the maximum size.

You must specify a value for the maximum size of the node group. The value must be an integer that is greater than or equal to 0 and less than or equal to 100, which is the maximum allowed size for a sole-tenant node group, and the value must be greater than or equal to the specified minimum value.

To accommodate workloads that might exceed the size maximum of 100 for a node group, create multiple node groups with matching affinity labels, for example, workload:in:my-autoscaled-node-groups. Then, schedule VMs using that affinity label, and enable autoscaling on each group to create a dynamically scaling group of node groups.

Availability

You can only use the sole-tenant node autoscaler in regions that support sole-tenant nodes.

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