When determining the compute capacity for a VMware Cloud Foundation (VCF) VI Workload

Domain, the goal is to calculate the usable resources available to support virtual machines (VMs) and

their workloads. This involves evaluating the physical compute resources (CPU, memory, storage)

and accounting for overheads, efficiency features, and configurations that impact resource

availability. Below, each option is analyzed in the context of VCF 5.2, with a focus on official

documentation and architectural considerations:

A . vSAN space efficiency feature enablement

This is a critical element to consider. VMware Cloud Foundation often uses vSAN as the primary

storage for VI Workload Domains. vSAN offers space efficiency features such as deduplication,

compression, and erasure coding (RAID-5/6). When enabled, these features reduce the physical

storage capacity required for VM data, directly impacting the usable storage resources available for

compute workloads. For example, deduplication and compression can significantly increase usable

capacity by eliminating redundant data, while erasure coding trades off some capacity for fault

tolerance. The VMware Cloud Foundation 5.2 Planning and Preparation documentation emphasizes

the need to account for vSAN policies and efficiency features when sizing storage, as they influence

the effective capacity available for VMs. Thus, this is a key factor in compute capacity planning.

B . VM swap file

The VM swap file is an essential consideration for compute capacity, particularly for memory

resources. In VMware vSphere (a core component of VCF), each powered-on VM requires a swap file

equal to the size of its configured memory minus any memory reservation. This swap file is stored on

the datastore (often vSAN in VCF) and consumes storage capacity. When calculating usable

resources, you must account for this overhead, as it reduces the available storage for other VM data

(e.g., virtual disks). Additionally, if memory overcommitment is used, the swap file size can

significantly impact capacity planning. The VMware Cloud Foundation Design Guide and vSphere

documentation highlight the importance of factoring in VM swap file overhead when determining

resource availability, making this a valid element to consider.

C . Disk capacity per VM

While disk capacity per VM is important for storage sizing, it is not directly a primary factor in

calculating usable compute resources for a VI Workload Domain in the context of this question. Disk

capacity per VM is a workload-specific requirement that contributes to overall storage demand, but

it does not inherently determine the usable CPU or memory resources of the domain. In VCF, storage

capacity is typically managed by vSAN or other supported storage solutions, and while it must be

sufficient to accommodate all VMs, it is a secondary consideration compared to CPU, memory, and

efficiency features when focusing on compute capacity. Official documentation, such as the VCF 5.2

Administration Guide, separates storage sizing from compute resource planning, so this is not one of

the top three elements here.

D . Number of 10GbE NICs per VM

The number of 10GbE NICs per VM relates to networking configuration rather than compute capacity

(CPU and memory resources). While networking is crucial for VM performance and connectivity in a

VI Workload Domain, it does not directly influence the calculation of usable compute resources like

CPU cores or memory. In VCF 5.2, networking design (e.g., NSX or vSphere networking) ensures

sufficient bandwidth and NICs at the host level, but per-VM NIC counts are a design detail rather

than a capacity determinant. The VMware Cloud Foundation Design Guide focuses NIC

considerations on host-level design, not VM-level compute capacity, so this is not a relevant element

here.

E . CPU/Cores per VM

This is a fundamental element in compute capacity planning. The number of CPU cores assigned to

each VM directly affects how many VMs can be supported by the physical CPU resources in the VI

Workload Domain. In VCF, compute capacity is based on the total number of physical CPU cores

across all ESXi hosts, with a minimum of 16 cores per CPU required for licensing (as per the VCF 5.2

Release Notes and licensing documentation). When calculating usable resources, you must consider

how many cores are allocated per VM, factoring in overcommitment ratios and workload demands.

The VCF Planning and Preparation Workbook explicitly includes CPU/core allocation as a key input

for sizing compute resources, making this a critical factor.

F . Number of VMs

While the total number of VMs is a key input for overall capacity planning, it is not a direct element

in calculating usable compute resources. Instead, it is a derived outcome based on the available CPU,

memory, and storage resources after accounting for overheads and per-VM allocations. The VMware

Cloud Foundation 5.2 documentation (e.g., Capacity Planning for Management and Workload

Domains) uses the number of VMs as a planning target, not a determinant of usable capacity. Thus, it

is not one of the top three elements for this specific calculation.

Conclusion:

The three elements that should be considered when calculating usable compute resources are vSAN

space efficiency feature enablement (A), VM swap file (B), and CPU/Cores per VM (E). These directly

impact the effective CPU, memory, and storage resources available for VMs in a VI Workload Domain.

Reference:

VMware Cloud Foundation 5.2 Planning and Preparation Workbook

VMware Cloud Foundation 5.2 Design Guide

VMware Cloud Foundation 5.2 Release Notes

VMware vSphere 8.0 Update 3 Documentation (for VM swap file and CPU allocation details)

VMware Cloud Foundation Administration Guide