Dell PowerStore Protecting Your Data

Snapshots

Snapshots are read-only, point-in-time copies of data of a volume, volume group, virtual machine, or file system. Creating a snapshot saves the state of the storage resource at that particular point-in-time. Using snapshots, you can protect your data locally and restore a storage resource to a previous state.

You can manually create snapshots at any time. It is also possible to configure snapshot rules as part of a protection policy and assign them to storage resources. The system automatically creates snapshots of the relevant resource according to the schedule specified in the protection policy.

As of PowerStore 3.5, you can create secure snapshots that cannot be manually deleted by an administrator or an intruder, and are automatically deleted only when they reach their expiration time. Secure snapshots provide an additional means of protection from ransomware attacks.

If data corruption occurs or data is accidentally deleted, you can recover the data from the snapshots or restore the volume or volume group to the point in time when the snapshot was created.

For file systems, you can create two access types of read-only file snapshot: protocol and .snapshot. The default access type is protocol, which can be exported as an SMB share, NFS export, or both. You can share and mount the snapshot on a client like any other file system. For .snapshot access types, you can access the files within the snapshot from the production file system in the .snapshot subdirectory of each directory.

You can also create write-order consistent and application consistent snapshots of volumes:

• Write-order consistent snapshots - PowerStore holds all writes on the volume group members to provide a uniform point-in-time copy, and ensures consistent protection across all member volumes. You can generate write-order consistent snapshots from the PowerStore Manager.
• Application consistent snapshots - You can create application consistent snapshots of a volume or a volume group using AppSync. When you create an application consistent snapshot, all incoming I/O for a given application is quiesced while the snapshot is created.

To verify whether a snapshot is write-order consistent or application consistent, look at the Write-Order Consistent and Application Consistent columns in the snapshot tables for a volume or volume group in PowerStore Manager.

Mapping snapshots to hosts is not supported in PowerStore. To allow a connected host to access a snapshot, you can create a thin clone - a writable, space-efficient copy of the snapshot - and map it to a host. You can update the thin clone from different snapshots using the refresh operation.

For details on the possible snapshot-related operations you can perform, using the PowerStore Manager, see the Snapshots chapter.