Merge pull request #88722 from mletalie/OSDOCS-12833

[OSDOCS-12833]Allow specification  of az zones for new/secondary machine pools

Author: EricPonvelle

modules/sdpolicy-am-gcp-compute-types.adoc

@@ -3,12 +3,12 @@
 // * osd_architecture/osd_policy/osd-service-definition.adoc
 :_mod-docs-content-type: CONCEPT
 [id="gcp-compute-types_{context}"]
-= Google Cloud compute types
+= Google Cloud instance types
 
 {product-title} offers the following worker node types and sizes on Google Cloud that are chosen to have a common CPU and memory capacity that are the same as other cloud instance types:
 [NOTE]
 ====
-`e2`, `a2`, and `a3` compute types are available for CCS only.
+`e2`, `a2`, and `a3` instance types are available for CCS only.
 ====
 
 .General purpose

osd_cluster_admin/osd_nodes/osd-nodes-machinepools-about.adoc

@@ -27,11 +27,63 @@ By default, a cluster is created with one machine pool. You can add additional m
 Multiple machine pools can exist on a single cluster, and they can each have different types or different size nodes.
 
 == Machine pools in multiple zone clusters
-When you create a machine pool in a multiple availability zone (Multi-AZ) cluster, that one machine pool has 3 zones. The machine pool, in turn, creates a total of 3 compute machine sets - one for each zone in the cluster. Each of those compute machine sets manages one or more machines in its respective availability zone.
+By default, when you create a machine pool in a multiple availability zone (Multi-AZ) cluster, that one machine pool has 3 zones. The machine pool, in turn, creates a total of 3 compute machine sets - one for each zone in the cluster. Each of those compute machine sets manages one or more machines in its respective availability zone.
 
 If you create a new Multi-AZ cluster, the machine pools are replicated to those zones automatically. If you add a machine pool to an existing Multi-AZ, the new pool is automatically created in those zones. Similarly, deleting a machine pool will delete it from all zones.
 Due to this multiplicative effect, using machine pools in Multi-AZ cluster can consume more of your project's quota for a specific region when creating machine pools.
 
+=== Deploying a machine pool in a single availability zone within a Multi-AZ cluster
+{product-title} on {GCP} users can deploy a single machine pool in a specific availability zone that is part of a Multi-AZ cluster using the {cluster-manager} CLI (`ocm`). This option is especially useful in situations where a desired instance type is not available in all availability zones of a specific region as well as when your cluster does not need more than one of the desired instance types.
+
+[IMPORTANT]
+====
+You cannot assign the default machine pool to a single availability zone during the provisioning of a Multi-AZ cluster.
+====
+
+.Prerequisites
+*  You installed the link:https://console.redhat.com/openshift/downloads[OpenShift Cluster Manager API command-line interface (`ocm`)].
+
+[IMPORTANT]
+====
+[subs="attributes+"]
+OpenShift Cluster Manager API command-line interface (`ocm`) is a Technology Preview feature only.
+For more information about the support scope of Red Hat Technology Preview features, see link:https://access.redhat.com/support/offerings/techpreview/[Technology Preview Features Support Scope].
+====
+
+.Procedure
+
+** Deploy a machine pool to a specific availability zone by running the following command:
+
+[source,terminal]
+----
+ocm create machine-pool \
+  --cluster <cluster_name|cluster_id> \ <1>
+  --instance-type <instance_type> \ <2>
+  --replicas <number_of_replicas> \ <3>
+  --availability-zone <availability_zone> \ <4>
+    [flags] \ <5>
+   <machine_pool_id> <6>
+
+----
+<1> Replace `<cluster_name|cluster_id>` with the name or ID of the cluster that you want to add the machine pool to.
+<2> Replace `<instance_type>` with the instance type you want to deploy to the single availability zone.
+<3> Replace `<replicas>` with the number of replicas of the selected instance type you want to include in the machine pool.
+<4> Replace `<availability_zone>` with the availability zone you want to add the machine pool to.
+<5> Optional: Replace [flags] with any additional flags available for machine pool creation.
+<6> Replace `<machine_pool_id>` with an ID for your machine pool.
+
+[NOTE]
+====
+To view the additional flags available for machine pool creation, run the `ocm create machine-pool --help` command.
+====
+
+
+For more information about {GCP} instance types and availability zones, see the _Additional resources_ section.
+
 [role="_additional-resources"]
 == Additional resources
 * xref:../../osd_cluster_admin/osd_nodes/osd-nodes-about-autoscaling-nodes.adoc#osd-nodes-about-autoscaling-nodes[About autoscaling]
+
+* xref:../../osd_architecture/osd_policy/osd-service-definition.adoc#gcp-compute-types_osd-service-definition[Google Cloud instance types]
+
+* xref:../../osd_architecture/osd_policy/osd-service-definition.adoc#gcp-regions-availability-zones_osd-service-definition[Google Cloud regions and availability zones]

osd_whats_new/osd-whats-new.adoc

@@ -19,6 +19,8 @@ With its foundation in Kubernetes, {product-title} is a complete {OCP} cluster p
 === Q1 2025
 
 * **New version of {product-title} available.** {product-title} on {gcp} and {product-title} on {aws} versions 4.18 are now available. For more information about upgrading to this latest version, see xref:../upgrading/osd-upgrades.adoc#osd-upgrades[Red Hat OpenShift Dedicated cluster upgrades].
+* **Support for assigning newly created machine pools to specific availability zones within a Multi-AZ cluster.**
+{product-title} on {GCP} users can now assign machine pools to specific availability zones using the {cluster-manager} CLI (`ocm`). For more information, see xref:../osd_cluster_admin/osd_nodes/osd-nodes-machinepools-about.adoc#deploying-a-machine-pool-in-a-single-availability-zone-within-a-multi-az-cluster[Deploying a machine pool in a single availability zone within a Multi-AZ cluster].
 
 * **Cluster node limit update.** {product-title} clusters versions 4.14.14 and greater can now scale to 249 worker nodes. This is an increase from the previous limit of 180 nodes. For more information, see xref:../osd_planning/osd-limits-scalability.adoc#osd-limits-scalability[limits and scalability].
 // * **{product-title} SDN network plugin blocks future major upgrades**