Verify that the ESXi hosts in your organization meet the vSAN hardware requirements.

Storage Device Requirements

All capacity devices, drivers, and firmware versions in your Virtual SAN configuration must be certified and listed in the Virtual SAN section of the VMware Compatibility Guide.

Table 1. Storage Device Requirements for vSAN Hosts
Storage Component Requirements
Cache
  • One SAS or SATA solid-state disk (SSD) or PCIe flash device.
  • Before calculating the Primary level of failures to tolerate, check the size of the flash caching device in each disk group. Verify that it provides at least 10 percent of the anticipated storage consumed on the capacity devices, not including replicas such as mirrors.
  • vSphere Flash Read Cache must not use any of the flash devices reserved for vSAN cache.
  • The cache flash devices must not be formatted with VMFS or another file system.
Virtual machine data storage
  • For hybrid group configuration, make sure that at least one SAS, NL-SAS, or SATA 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.
Storage controllers One SAS or SATA host bus adapter (HBA), or a RAID controller that is in passthrough mode or RAID 0 mode.

Memory

The memory requirements for vSAN depend on the number of disk groups and devices that the ESXi hypervisor must manage. Each host must contain a minimum of 32 GB of memory to accommodate the maximum number of disk groups (5) and maximum number of capacity devices per disk group (7).

Flash Boot Devices

During installation, the ESXi installer creates a coredump partition on the boot device. The default size of the coredump partition satisfies most installation requirements.
  • If the memory of the ESXi host has 512 GB of memory or less, you can boot the host from a USB, SD, or SATADOM device. When you boot a vSAN host from a USB device or SD card, the size of the boot device must be at least 4 GB.
  • If the memory of the ESXi host has more than 512 GB, you must boot the host from a SATADOM or disk device. When you boot a vSAN host from a SATADOM device, you must use single-level cell (SLC) device. The size of the boot device must be at least 16 GB.
Note: vSAN 6.5 and later enables you to resize an existing coredump partition on an ESXi host in a vSAN cluster, so you can boot from USB/SD devices. For more information, see the VMware knowledge base article at http://kb.vmware.com/kb/2147881.

When you boot an ESXi 6.0 or later host from USB device or from SD card, vSAN trace logs are written to RAMDisk. These logs are automatically offloaded to persistent media during shutdown or system crash (panic). This is the only support method for handling vSAN traces when booting an ESXi from a USB stick or SD card. If a power failure occurs, vSAN trace logs are not preserved.

When you boot an ESXi 6.0 or later host from a SATADOM device, vSAN trace logs are written directly to the SATADOM device. Therefore it is important that the SATADOM device meets the specifications outlined in this guide.