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
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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
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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.
