Merge pull request #28472 from sjhala-ccs/cnv-6891

CNV-6891 Documented additional hardware requirements imposed by CNV

Author: aburdenthehand

modules/virt-cluster-resource-requirements.adoc

@@ -0,0 +1,83 @@
+// Module included in the following assemblies:
+//
+// * virt/install/preparing-cluster-for-virt.adoc
+
+[id="virt-cluster-resource-requirements_{context}"]
+= Additional hardware requirements for {VirtProductName}
+
+
+{VirtProductName} is an add-on to {product-title} and imposes additional overhead that you must account for when planning a cluster. Each cluster machine must accommodate the following overhead requirements in addition to the {product-title} requirements. Oversubscribing the physical resources in a cluster can affect performance.
+
+[IMPORTANT]
+====
+The numbers noted in this documentation are based on Red Hat’s test methodology and setup. These numbers can vary based on your own individual setup and environments.
+====
+
+[id="memory-overhead_{context}"]
+== Memory overhead
+
+Calculate the memory overhead values for {VirtProductName} by using the equations below.
+
+.Cluster memory overhead
+
+----
+Memory overhead per infrastructure node ≈ 150 MiB
+----
+
+----
+Memory overhead per worker node ≈ 360 MiB
+----
+
+Additionally, {VirtProductName} environment resources require a total of 2179 MiB of RAM that is spread across all infrastructure nodes.
+
+
+.Virtual machine memory overhead
+
+----
+Memory overhead per virtual machine ≈ (1.002 * requested memory) + 146 MiB  \
+                + (8 * number of vCPUs) + (16 MiB * number of graphics devices)
+----
+
+Add 1 GiB to the above result if your environment includes a Single Root I/O Virtualization (SR-IOV) network device or a Graphics Processing Unit (GPU).
+
+
+[id="CPU-overhead_{context}"]
+== CPU overhead
+
+Calculate the cluster processor overhead requirements for {VirtProductName} by using the equation below. The CPU overhead per virtual machine depends on your individual setup.
+
+.Cluster CPU overhead
+
+----
+CPU overhead for infrastructure nodes ≈ 4
+----
+
+----
+CPU overhead for worker nodes ≈ 2 + CPU overhead per virtual machine
+----
+
+.Virtual machine CPU overhead
+
+CPU overhead per virtual machine is subjective. If dedicated CPUs are requested, there is a 1:1 impact on the cluster CPU overhead requirement. Otherwise, there are no specific rules about how many CPUs a virtual machine requires.
+
+
+[id="storage-overhead_{context}"]
+== Storage overhead
+
+Use the guidelines below to estimate storage overhead requirements for your {VirtProductName} environment.
+
+.Cluster storage overhead
+
+----
+Aggregated storage overhead per node ≈ 10.36 GiB
+----
+
+.Virtual machine storage overhead
+
+Storage overhead per virtual machine depends on specific requests for resource allocation within the virtual machine. The request could be for ephemeral storage on the node or storage resources hosted elsewhere in the cluster. {VirtProductName} does not currently allocate any additional ephemeral storage for the running container itself.
+
+
+[id="example-scenario_{context}"]
+== Example
+
+As a cluster administrator, if you plan to host 10 virtual machines in the cluster, each with 1 GiB of RAM and 2 vCPUs, the memory impact across the cluster is 11.68 GiB.

virt/install/preparing-cluster-for-virt.adoc

@@ -31,3 +31,5 @@ In {VirtProductName} clusters installed using installer-provisioned infrastructu
 To obtain an evaluation version of {product-title}, download a trial
 from the {product-title} home page.
 ====
+
+include::modules/virt-cluster-resource-requirements.adoc[leveloffset=+1]