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Dell offers Embedded NAS (eNAS) Guest OS (GOS) on the PowerMax 2000 and 8000, and Embedded File GOS on the PowerMax 2500/8500. NAS on the PowerMax enables customers to leverage vital Tier 1 features including SLO-based provisioning, Host I/O Limits, and data reduction technologies. eNAS consists of virtual instances of VNX Software Data Movers and Control Stations that run on the PowerMax. File is a new implementation that is being used across different arrays in the portfolio.
Unlike block storage, file storage does not support VAAI as part of the array code. All NFS file systems, regardless of vendor, require a NAS plug-in. Fortunately, the plug-in code is generic. The same plug-in that is used for the Dell Unity platform can be used for other arrays like PowerMax and PowerStore. The plug-in works with either NFS version 3 or 4.1.
The VAAI features for NAS are not exactly equivalent to the features that are available on block. The idea is the same: to offload tasks to the array. Features on NAS include NFS Clone Offload, extended stats, space reservations, and snap of a snap. In essence, the NFS clone offload works similarly to XCOPY as it offloads ESXi clone operations to the array.
There are three different versions of the plug-in depending on which ESXi version that is running: 3.0.1 for 6.7 and above, 3.0.2 for 7.0 and above and 4.0.1 for 7.0.1 and above. Version 4.0.1 is the only one that does not require a reboot after installation. To install the plug-in, download the NAS plug-in from Dell support. The plug-in is delivered as a VMware Installation Bundle (VIB). The plug-in can be installed through VMware vCenter Update Manager or through the CLI as demonstrated in Figure 156. Be sure to check for any existing NAS plug-in as it must be removed before installing the new one. Stop and start the vaai-nasd service if installing version 4.0.1 as below. Otherwise, reboot for the other versions.
Note: VAAI with eNAS is only supported on NFS version 3 and not NFS version 4.1. VAAI supports both versions 3 and 4.1 with PowerMax File.
Once installed, the vSphere Client shows that VAAI is supported on the NFS datastores as in Figure 157. If the plug-in is not installed, the column shows as "Unknown."
As mentioned, one of the other VAAI integrations for NFS is extended stats. Using vmkfstools the user can display the disk utilization for virtual machine disks that are configured on NFS datastores. The extendedstat argument provides disk details for the virtual disks. The command reports, in bytes, virtual disk size, used space, and unshared space. An example is shown in Figure 158.
Another VAAI capability on NFS is the ability to create a thin-clone virtual machine from an existing thin-clone virtual machine. This functionality is known as nested clones. The functionality uses the snapshot architecture to instantaneously create lightweight virtual machine clones. VMware products such as Horizon can initiate these nested snapshots. The clone operations are off-loaded to the array. To take advantage of this feature with eNAS, enable the nested clone support property when you create the file system for eNAS. It cannot be changed after the file system is created. File enables the capability to do so automatically upon file system creation.