Dell PowerStore 1200T EMC PowerStore Protecting Your Data - Page 12

Using clones to access read-only snapshots from hosts Mapping and unmapping block snapshots to hosts is not supported in PowerStore. To allow a connected host to access a snapshot, create a thin clone of the snapshot and map it to a host. After creating the thin clone, you can use the refresh operation to update the thin clone from different snapshots. For more information, see Refresh a storage resource. File snapshots can be mounted on hosts either directly (to allow read-only access) or by creating a thin clone (to allow read-write access). To mount the file system directly, the snapshots can be exported as NFS export or SMB share. You can export snapshots using one of the following access types: ● Protocol - The snapshot is exported with a new share name. ● .snapshot - You can see the snapshot on Unix/Linux under the .snapshot directory of the file system, and on Windows, by right-clicking the file system and selecting the Previous Version option. Refresh a storage resource The refresh operation is used to replace the contents of a storage resource with contents from a related resource (a clone or an indirect child snapshot). You can create a duplicate of the production environment to be used for various purposes (such as test and development, reporting etc.). To keep the duplicated environment up-to-date, it should be updated with a storage resource that includes the recent changes. You can use the refresh operation in the following scenarios: ● Refresh a thin clone from the base volume. ● Refresh a storage resource or thin clone from another thin clone in the family. ● Refresh a storage resource or thin clone from a snapshot of a related thin clone or base volume. For file systems, you can refresh a snapshot of a file system with its direct parent file system. If you refresh the thin clone of a snapshot that has derivative snapshots, the derivative snapshots remain unchanged and the family hierarchy stays intact. If you refresh a volume group, the point-in-time image on all member volumes is also refreshed. When refreshing a resource from a snapshot that was replicated from a remote system, check the creation time and source data time values to ensure that you are using the correct snapshot. The Source Data Time value of replicated snapshots reflects the original source data time, and the Creation Time value is updated to the time of replication. NOTE: Because the refresh operation replaces the contents of a storage resource, it is recommended to take a snapshot of the resource before refreshing it. Creating a backup allows you to revert to a previous point in time. Before refreshing a snapshot, it is mandatory to shut down the application and unmount the volume or file system that is running on the production host, and then flush the host cache to prevent data corruption during the refresh operation. Refresh a volume using a snapshot About this task To refresh a volume using a snapshot: Steps 1. Open the volume list window. 2. Click the volume from which the snapshot was taken to open its Overview window. 3. Click the Protection tab, and then click Snapshots. 4. From the snapshots list, select the snapshot you want to use for the refresh operation. 5. Click More Actions > Refresh using Snapshot. 6. In the Refresh using Snapshot slide-out panel, select the volume or clone you want to refresh from the Volume being refreshed drop-down list. 7. Select whether to create a backup snapshot for the refreshed volume (the option is selected by default). 12 Snapshots