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One of the benefits of using array-based storage instead of vSAN for workload domains is the ability to use the features of the array, such as local replication. VMware does offer VM-based snapshots, but they are unable to offer a consistent copy of all objects that are part of the NFS datastore like array technology can. Such copies can serve multiple purposes, from cloning, to restores and backups. And as workload domains are designed to run production applications, it is essential to have a backup strategy in case of failure.
PowerFlex offers snapshot capability for all NFS file systems through both UI and CLI. The following walks through creating a snapshot in the UI interface.
In the UI, log in and go to File > File Systems. Then, select the desired file system where the workload domain will be provisioned, in this case nfs-wkld. Select Protection > Create Snapshot from the menu as in Figure 25.
Figure 25. File system snapshot
PowerFlex presents the following three types of snapshots shown in Figure 26:
The retention period is set to one week by default. One can set a different retention period or select the No Automatic Deletion for indefinite retention.
Figure 26. Snapshot options
For the purposes of backup and restore, a protocol (read-only) snapshot is the best option because it is only mounted when required and does not permit overwriting the data. A protocol (read/write) snapshot would be useful for test or development purposes. Finally, the “snapshot” snapshot, unlike the other two, is made available immediately to the system through the existing NFS file system. This type of snapshot is useful to do a quick restore of objects in the file system since it is made immediately available. In VMware, the way to access it is through the snapshot directory of the NFS datastore. This directory does not show up, even when listing hidden files. The user must know that the snapshot exists and change the directory into it. Alternatively, if the same NFS datastore is also available as an SMB share, the snapshot is available by right clicking the share, selecting Properties and then the Previous Versions tab as seen in Figure 27.
Figure 27. Snapshot access in an SMB share
By opening the folder, the objects in the snapshot are available for restore. If restoring VMs, be sure to first shut them down and unregister them, to avoid any issues.
In additional to individual snapshots, PowerFlex provides the ability to setup protection policies which consist of snapshot rules that automate how often to take snapshots of an NFS file system and how long to retain them. An NFS file system may only have a single protection policy assigned to it. To create a protection policy:
These steps are shown in Figure 28.
Figure 28. Create protection policy
In the example in Figure 29, the rule is set to take a read-only snapshot every four hours and retain the snapshots on a cycle of 120 hours. This leads to 30 snapshots being taken before the first snapshot taken is removed.
Figure 29. Create Rule
The rule is assigned automatically to the policy.
Figure 30. Create policy - Complete
The final step is to assign the newly created policy to the workload file system.
Figure 31. Assign protection policy
Figure 32. Assign policy
The policy is now applied and PowerFlex will take the snapshots automatically, providing local replication for backups, restores, and cloning. The installation of the workload can now proceed on the protected file system.