Home > Storage > PowerMax and VMAX > Storage Admin > Using Dell PowerMax with Linux KVM Implementation Guide > Protection for KVM on PowerMax
A benefit of using array-based storage for KVM is the ability to use the features of the array, such as local and remote replication. While KVM does offer the ability to take virtual machine-based snapshots, it cannot take a snapshot of the entire storage domain. Such copies can serve multiple purposes, from cloning, to restores and backups. Because storage domains are used to run production applications, it is essential to have a backup strategy in case there is a failure.
PowerMax offers remote replication and snapshot capability for block and file storage through both the UI and the CLI. While remote replication is beyond the scope of this guide, the following sections describe how to create a snapshot in the PowerMax UI for both a block volume and a file system that are in use as storage domains. In addition, snapshot policies are covered.
FC and iSCSI support block snapshots.
To create a block snapshot:
Figure 77. Create snapshot – set protection
Figure 78. Create snapshot – select technology
Figure 79. Create snapshot – configure SnapVX
Figure 80. Create snapshot – view summary
Unisphere establishes the snapshot. Figure 81 show the message for a successful completion:
Figure 81. Successful snapshot
After the snapshot is created, it can be linked to a target volume and presented in a masking view to other KVM hosts. Then it is available for use with the oVirt functionality such as importing the storage domain.
To create a file system snapshot:
Figure 82. File system snapshot – choose the file system
Figure 84. File system snapshot – define the snapshot
For backup and restore purposes, a default protocol snapshot is the best option because it is only mounted when required and does not permit overwriting the data. The .Snapshot snapshot, unlike the Protocol snapshot, is available immediately to the system through the existing NFS file system. This type of snapshot is useful to restore objects quickly in the file system. In Linux, access to the snapshot is through the “.snapshot” directory of the NFS datastore. This directory is not displayed, even when listing hidden files. The user must know that the snapshot exists, and the user must change the directory into .snapshot.
Figure 85. Snapshot access in an SMB share
By opening the folder, the objects in the snapshot are available to restore.
In addition to individual snapshots, in Unisphere the user can set up protection policies that consist of snapshot rules that automate how often to take a snapshot of a storage group or file system, and how long to retain them. A storage group or file system might only have a single protection policy that is assigned to it. Because both block and file protection policies are similar, it is unnecessary to include both.
To create a protection policy for a file system:
Figure 86. Create protection policy
Figure 87. Attach a snapshot policy to the file system
Figure 88. Attach snapshot policy to the file system – select snapshot policy
The policy remains in effect for that file system until it is either detached, or the snapshot policy itself is disabled.