With the hardware acceleration, ESXi hosts can integrate with NAS devices and use several hardware operations 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.
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.
Native Snapshot Support. Creation of virtual machine snapshots can be offloaded to the array.
Extended Statistics. Supports visibility to space use on NAS devices. 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 VIB packages through a website. No claim rules are required for the NAS plug-ins to function.
Several tools for installing and upgrading VIB packages are available. They include the esxcli commands and vSphere Update Manager. For more information, see the vSphere Upgrade and Installing and Administering VMware vSphere Update Manager documentation.