You can use thin-provisioned storage arrays with ESXi.

The ESXi host integrates with block-based storage and performs these tasks:
  • The host can recognize underlying thin-provisioned LUNs and monitor their space use to avoid running out of physical space. The LUN space might change if, for example, your VMFS datastore expands or if you use Storage vMotion to migrate virtual machines to the thin-provisioned LUN. The host warns you about breaches in physical LUN space and about out-of-space conditions.
  • The host can run the automatic T10 unmap command from VMFS6 and VM guest operating systems to reclaim unused space from the array. VMFS5 supports a manual space reclamation method.
Note: ESXi does not support activating or deactivating of thin provisioning on a storage device.

Requirements

To use the thin provisioning reporting and space reclamation features, follow these requirements:

  • Use an appropriate ESXi version.
    Supported thin provisioning components ESXi 6.5 and later
    Thin provisioning Yes
    Unmap command originating from VMFS Automatic for VMFS6
    Unmap command originating from guest OS Yes (VMFS6)
  • Use storage systems that support T10-based vSphere Storage APIs - Array Integration (VAAI), including thin provisioning and space reclamation. For information, contact your storage provider and check the VMware Compatibility Guide documentation.

Monitoring Space Use

The thin provision integration functionality helps you to monitor the use of space on thin-provisioned LUNs and to avoid running out of space.

The following sample flow demonstrates how the ESXi host and the storage array interact to generate breach of space and out-of-space warnings for a thin-provisioned LUN. The same mechanism applies when you use Storage vMotion to migrate virtual machines to the thin-provisioned LUN.

  1. Using storage-specific tools, your storage administrator provisions a thin LUN and sets a soft threshold limit that, when reached, triggers an alert. This step is vendor-specific.
  2. Using the vSphere Client, you create a VMFS datastore on the thin-provisioned LUN. The datastore spans the entire logical size that the LUN reports.
  3. As the space used by the datastore increases and reaches the set soft threshold, the following actions take place:
    1. The storage array reports the breach to your host.
    2. Your host triggers a warning alarm for the datastore.

      You can contact the storage administrator to request more physical space. Alternatively, you can use Storage vMotion to evacuate your virtual machines before the LUN runs out of capacity.

  4. If no space is left to allocate to the thin-provisioned LUN, the following actions take place:
    1. The storage array reports out-of-space condition to your host.
      Caution:

      In certain cases, when a LUN becomes full, it might go offline or get unmapped from the host.

    2. The host pauses virtual machines and generates an out-of-space alarm.

      You can resolve the permanent out-of-space condition by requesting more physical space from the storage administrator.

Identify Thin-Provisioned Storage Devices

Use the esxcli command to verify whether a particular storage device is thin-provisioned.

Prerequisites

Install ESXCLI. See Getting Started with ESXCLI. For troubleshooting, run esxcli commands in the ESXi Shell.

Procedure

  • ♦ Run the esxcli storage core device list -d=device_ID command.

Results

The following thin provisioning status indicates that the storage device is thin-provisioned. 
# esxcli storage core device list -d naa.XXXXXXXXXXXX4c
naa.XXXXXXXXXXXX4c
 Display Name: XXXX Fibre Channel Disk(naa.XXXXXXXXXXXX4c)
 Size: 20480
 Device Type: Direct-Access
 Multipath Plugin: NMP
 ---------------------
 Thin Provisioning Status: yes
 ---------------------
An unknown status indicates that a storage device is thick.
Note: Some storage systems present all devices as thin-provisioned no matter whether the devices are thin or thick. Their thin provisioning status is always yes. For details, check with your storage vendor.