With the hardware acceleration, ESXi hosts can integrate with NAS devices and use several hardware operations, such as Full File Clone and Fast File Clone that NAS storage provides. The hardware acceleration uses vSphere APIs for Array Integration (VAAI) to facilitate communications between the hosts and storage devices.

The VAAI NAS framework supports both versions of NFS storage, NFS 3 and NFS 4.1.

The VAAI NAS uses a set of storage primitives to offload storage operations from the host to the array. The following list shows the supported NAS operations:

Full File Clone
Supports an ability of NAS device to clone virtual disk files. This operation is similar to the VMFS block cloning, except that NAS devices clone entire files instead of file segments. Tasks that benefit from the full file clone operation include VM cloning, Storage vMotion, and deployment of VMs from templates.

When the ESXi host copies data with VAAI NAS, it does not need to read the data from the NAS and write back the data to the NAS. The host simply sends the copy command offloading it to the NAS. The copy process is done in the NAS, which reduces the load on the host.

Fast File Clone
This operation, also called array-based or native snapshots, offloads creation of virtual machine snapshots and linked clones to the array.
Reserve Space
Supports an ability of storage arrays to allocate space for a virtual disk file in the thick format.

Typically, when you create a virtual disk on an NFS datastore, the NAS server determines the allocation policy. The default allocation policy on most NAS servers is thin and does not guarantee backing storage to the file. However, the reserve space operation can instruct the NAS device to use vendor-specific mechanisms to reserve space for a virtual disk. As a result, you can create thick virtual disks on the NFS datastore if the backing NAS server supports the reserve space operation.

Extended Statistics
Supports visibility to space use on NAS devices. The operation enables you to query space utilization details for virtual disks on NFS datastores. The details include the size of a virtual disk and the space consumption of the virtual disk. This functionality is useful for thin provisioning.

With NAS storage devices, the hardware acceleration integration is implemented through vendor-specific NAS plug-ins. These plug-ins are typically created by vendors and are distributed as vendor packages. No claim rules are required for the NAS plug-ins to function.

Several tools for installing and updating NAS plug-ins are available. They include the esxcli commands and vSphere Lifecycle Manager. For more information, see the VMware ESXi Upgrade and Managing Host and Cluster Lifecycle documentation. For installation and update recommendations, see the Knowledge Base article.

Note: NAS storage vendors might provide additional settings that can affect the performance and operation of VAAI. Follow the vendor's recommendations and configure the appropriate settings on both the NAS storage array and ESXi. See your storage vendor documentation for more information.

Enable NAS Native Snapshots on Virtual Machines

If your deployment includes NAS arrays that support the vSphere APIs for Array Integration (VAAI), you can use the fast file clone technology, also called native NFS snapshots, to make virtual machine snapshots. With this technology, the NFS device copies the virtual machine without having the ESXi host read and write the data. This operation might reduce the time and network load when VM snapshots are created.

By default, all newly created VMs support traditional ESXi snapshot technology. To use the NFS native snapshot technology, enable it for the VM.

Prerequisites

  • Verify that the NAS array supports the fast file clone operation with the VAAI NAS program.
  • On your ESXi host, install vendor-specific NAS plug-in that supports the fast file cloning with VAAI.
  • Follow the recommendations of your NAS storage vendor to configure any required settings on both the NAS array and ESXi. See your storage vendor documentation for more information.

Procedure

  1. In the vSphere Client, right-click the virtual machine and select Edit Settings.
  2. Click the VM Options tab and expand the Advanced menu.
  3. Click Edit Configuration next to Configuration Parameters.
  4. Configure the snapshot.alwaysAllowNative parameter.
    If the parameter exists, make sure that its value is set to True. If the parameter is not present, add it and set its value to True.
    Name Value
    snapshot.alwaysAllowNative True
    Note: VMs stored on NFS datastores and configured with snapshot.alwaysAllowNative might encounter the Invalid Disk Chain error. For more information, see the VMware Knowledge Base article 89923.