vSphere Cluster Design for the Management Domain

The cluster design must consider the characteristics of the management workloads that are deployed in the management cluster.

When you design the cluster layout in vSphere, consider the following guidelines:

• Use fewer, larger ESXi hosts, or more, smaller ESXi hosts.

  • A scale-up cluster has fewer, larger ESXi hosts.

  • A scale-out cluster has more, smaller ESXi hosts.

• Compare the capital costs of purchasing fewer, larger ESXi hosts with the costs of purchasing more, smaller ESXi hosts. Costs vary between vendors and models. Evaluate the risk of losing one larger host in a scale-up cluster and the impact on the business with the higher change to lose one or more small hosts in scale-out cluster.

• Evaluate the operational costs for managing a few ESXi hosts with the costs of managing more ESXi hosts.

• Consider the purpose of the cluster.

• Consider the total number of ESXi hosts and cluster limits.

Figure 1. vSphere Logical Cluster Layout with a Single Availability Zone for the Management Domain

Figure 2. vSphere Cluster Layout for Multiple Availability Zones for the Management Domain

Table 1. Number of Hosts in the Default Management Cluster

Attribute	Specification
Minimum number of ESXi hosts required for the management domain	Single availability zone	4
	Two availability zones	8
Reserved capacity for handling ESXi host failures per cluster	Single availability zone	25% CPU and RAM Tolerates one host failure.
	Two availability zones	50% CPU and RAM Tolerates one availability zone failure.

Table 2. Design Decisions on the Configuration of the Default Cluster in a Management Domain with a Single Availability Zone

Decision ID	Design Decision	Design Justification	Design Implication
VCF-MGMT-VCS-CLS-001	Create a cluster in the management domain for the initial set of ESXi hosts.	Simplifies configuration by isolating management workloads from tenant workloads. Ensures that tenant workloads have no impact on the management stack. You can add ESXi hosts to the cluster as needed.	Management of multiple clusters and vCenter Server instances increases operational overhead.
VCF-MGMT-VCS-CLS-002	Allocate a minimum of 4 ESXi hosts for the default management cluster.	Allocating 4 ESXi hosts provides N+1 redundancy to protect against host failure in the cluster. Having 4 ESXi hosts also guarantees redundancy for vSAN and NSX-T Data Center during maintenance operations.	To support redundancy, you must allocate additional ESXi host resources.

Table 3. Design Decisions on the Configuration of the Default Cluster in a Management Domain with Multiple Availability Zones

Decision ID	Design Decision	Design Justification	Design Implication
VCF-MGMT-VCS-CLS-003	Add 4 ESXi hosts to create the second availability zone of default management cluster. The total number of ESXi hosts in the default cluster of the management domain across the two availability zones is eight.	Allocating 4 ESXi hosts provides N+1 redundancy for each availability zone to protect against host failure in the cluster. Having 4 ESXi hosts in each availability zone guarantees redundancy for vSAN and NSX-T Data Center during availability zone outages or maintenance operations.	To support redundancy, you must allocate additional ESXi host resources.

Table 4. Design Decisions on the Host Configuration for the Default Management Cluster for Multiple VMware Cloud Foundation Instances

Decision ID	Design Decision	Design Justification	Design Implication
VCF-MGMT-VCS-CLS-004	In each subsequent VMware Cloud Foundation instance, create the default management cluster with a minimum of 4 ESXi hosts.	Allocating 4 ESXi hosts provides N+1 redundancy for the cluster. Having 4 ESXi hosts guarantees vSAN and NSX redundancy during maintenance operations.	To support redundancy, you must allocate additional ESXi host resources .