In addition to regular storage hard disk drives (HDDs), ESXi supports flash storage devices.

Unlike regular HDDs that are electromechanical devices containing moving parts, flash devices use semiconductors as their storage medium and have no moving parts. Typically, the flash devices are resilient and provide faster access to data.

To detect flash devices, ESXi uses an inquiry mechanism based on T10 standards. Check with your vendor whether your storage array supports the ESXi mechanism of flash device detection.

After the host detects the flash devices, you can use them for several tasks and functionalities.

If you use NVMe storage, enable the high-performance plug-in (HPP) to improve your storage performance. See VMware High Performance Plug-In and Path Selection Schemes.

For specifics about using NVMe storage with ESXi, see About VMware NVMe Storage.

Table 1. Using Flash Devices with ESXi
Functionality Description
vSAN vSAN requires flash devices. For more information, see the Administering VMware vSAN documentation.
VMFS Datastores Create VMFS datastores on flash devices. Use the datastores for the following purposes:
  • Store virtual machines. Certain guest operating systems can identify virtual disks stored on these datastores as flash virtual disks.
  • Allocate datastore space for the ESXi host swap cache. See Configure Host Cache with VMFS Datastore.
Virtual Flash Resource (VFFS) If required by your vendor, set up a virtual flash resource and use it for I/O caching filters. See Filtering Virtual Machine I/O.

Flash Devices and Virtual Machines

Guest operating systems can identify virtual disks that reside on flash-based datastores as flash virtual disks.

Guest operating systems can use standard inquiry commands such as SCSI VPD Page (B1h) for SCSI devices and ATA IDENTIFY DEVICE (Word 217) for IDE devices.

For linked clones, native snapshots, and delta-disks, the inquiry commands report the virtual flash status of the base disk.

Operating systems can detect that a virtual disk is a flash disk under the following conditions:
  • Detection of flash virtual disks is supported on VMs with virtual hardware version 8 or later.
  • Devices backing a shared VMFS datastore must be marked as flash on all hosts.
  • If the VMFS datastore includes several device extents, all underlying physical extents must be flash-based.