VMware Specialist: vSAN 6.x - Objective 2.2 - Describe vSAN Requirements

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Certification VMware Specialist vSAN

Published on 5 April 2018 by Christopher Lewis. Words: 573. Reading Time: 3 mins.

The following post is a part of my unofficial study guide for the VMware Specialist: vSAN 2017 Digital Badge. The full study guide can be found here.

Objective 2.2 - Describe vSAN Requirements

The requirements for VMware vSAN are split into multiple categories:

  • Hardware
  • Cluster
  • Software
  • Networking
  • Licensing

Hardware Requirements

One of the most important requirements in VMware vSAN is that all hardware components (i.e. cache devices, capacity devices, drivers, and firmware versions) in VMware vSAN must be certified for VMware vSAN AND listed in the vSAN section of the VMware Compatibility Guide.

Storage Devices

There are two types of Storage Devices within VMware vSAN:

  • Cache Devices
  • Capacity Devices

Each host has a combination of multiple Cache and Capacity Devices that are configured into Disk Groups.

Cache Devices

  • One Cache Device is required per Disk Group.
  • One SAS or SATA solid-state disk (SSD) or PCIe flash device.
  • Maximum number of Cache Devices is 5.

Capacity Devices

  • Up to seven Capacity Devices are required per Disk Group.
  • For hybrid group configuration, make sure that at least one SAS or NL-SAS magnetic disk is available.
  • For** all-flash** disk group configuration, make sure at least one SAS, or SATA solid-state disk (SSD), or PCIe flash device.
  • Maximum number of Capacity Devices (for 5 Disk Groups) is 35.

Storage Controllers

  • One SAS or SATA host bus adapter (HBA), or a RAID controller that is in Passthrough (JBOD) mode or RAID 0 mode.
  • If the same Storage Controller contains Non-vSAN disks, the RAID (or Passthrough) configuration should be maintained for all Non-vSAN disks.
  • For Non-vSAN disks using the same Storage Controller:
    • Do not use Passthrough disks for RDM
    • Do not run VMs from the Non-vSAN disks/datastores.
  • All Controllers should be on the supported list.
  • Check Manufacturer information for further configuration information.


Within VMware vSAN, each Disk Group has an overhead in terms of memory (RAM). To support the maximum number of Disk Groups (5) and the maximum number of capacity devices per Disk Group (7), each vSAN node must contain a minimum of 32GB RAM.

Flash Boot Devices

  • When deploying VMware vSAN, boot from USB, SD or SATADOM.
  • If a host has < 512GB RAM, then the boot device must be > 4GB.
  • If a host has > 512GB RAM, then the boot device must be > 16GB.
  • If booting from USB or SD, logs are written to the RAMDISK and are offloaded to persistent storage.
  • If booting from SATADOM, logs are written directly to the device.

Cluster Requirements

  • All host hardware must be listed on the VMware Compatibility Guide.
  • All hosts should have identical hardware configuration.
  • A vSAN Cluster has a minimum of 3 hosts/nodes.
  • A vSAN Cluster has a maximum of 64 hosts/nodes.

Software Requirements

  • All hosts should have the same version of VMware vSphere.
  • For all of the latest features, the latest version of vSphere (6.5) should be deployed.

Network Requirements

  • For All-Flash and Hybrid vSAN the recommendation is for 10GbE.
  • Hybrid vSAN has a minimum requirement of 1GbE.
  • Each host in the vSAN cluster, regardless of whether it contributes capacity, must have a VMkernel network adapter for vSAN traffic.
  • All hosts in the vSAN cluster must be connected to a vSAN Layer 2 or Layer 3 network.
  • Both IPv4 and IPv6 is supported for the vSAN Network..

Licensing Requirements

  • vSAN is licensed separately to VMware vSphere.
  • There are Standard, Advanced and Enterprise edition licensing.
  • All CPUs must be licensed within the vSAN cluster.