// Module included in the following assemblies:
//
// * updating/understanding_updates/how-updates-work.adoc

:_mod-docs-content-type: CONCEPT
[id="update-evaluate-availability_{context}"]
= Evaluation of update availability

The Cluster Version Operator (CVO) periodically queries the OpenShift Update Service (OSUS) for the most recent data about update possibilities.
This data is based on the cluster's subscribed channel.
The CVO then saves information about update recommendations into either the `availableUpdates` or `conditionalUpdates` field of its `ClusterVersion` resource.

The CVO periodically checks the conditional updates for update risks.
These risks are conveyed through the data served by the OSUS, which contains information for each version about known issues that might affect a cluster updated to that version.
Most risks are limited to clusters with specific characteristics, such as clusters with a certain size or clusters that are deployed in a particular cloud platform.

The CVO continuously evaluates its cluster characteristics against the conditional risk information for each conditional update. If the CVO finds that the cluster matches the criteria, the CVO stores this information in the `conditionalUpdates` field of its `ClusterVersion` resource.
If the CVO finds that the cluster does not match the risks of an update, or that there are no risks associated with the update, it stores the target version in the `availableUpdates` field of its `ClusterVersion` resource.

The user interface, either the web console or the OpenShift CLI (`oc`), presents this information in sectioned headings to the administrator.
Each *supported but not recommended* update recommendation contains a link to further resources about the risk so that the administrator can make an informed decision about the update.
