For volume and volume group thin clones, a refresh operation replaces the contents of the thin clone with the data of another resource within the same family. For volume group thin clones with write-order consistency enabled, the contents for all members of the group are replaced. When write-order consistency is disabled, individual volumes within a volume group can be refreshed. After a refresh operation is started, the process completes quickly, as only pointer updates for the resource are changed. A storage resource family contains the parent storage resource, which is the original resource, thin clones, and snapshots in the tree. An example is shown in Figure 39.

Figure 39.    Storage resource family example

When using a refresh operation, it is highly suggested to shut down applications using the volume, take the volume offline on the hosts, and take a backup snapshot of the current state of the resource. Not only does this guard against corruption, but it also preserves a point-in-time copy of the dataset in case it is needed. When a refresh operation is issued from PowerStore Manager, an option to take a backup snapshot is provided. This option, which is selected by default, takes a backup right before the refresh operation is started.

Table 3 outlines the refresh operations that are allowed for volumes and volume group thin clones. The table is organized by the object to refresh, the object to refresh from, and if the operation is allowed. Notes below the table provide more information about the supported operations.

Table 3.      Volume and volume group refresh operations

1 Refreshing from a snapshot of a peer, in-family, thin clone snapshot is also supported.

To refresh a volume or volume group thin clone from another resource, select the volume or volume group thin clone from the resource list page, select Repurpose, and select Refresh Using Related Volume. In previous versions of PowerStoreOS, this option was found under the More Actions dropdown. In the following example, the resources in Figure 39 were re-created to show the objects that can be used as a source of the refresh operation.

After Snap 1 Thin Clone, Repurpose, and Refresh Using Related Volume is selected, the screen in Figure 40 is shown.

In this window, a warning is shown to remind the user to shut down applications using the volume and take the volume offline on the hosts. These operations should be performed prior to the refresh operation to prevent data integrity issues. The user is also provided information about the resource being refreshed, and a drop-down to select the source of the new data. The Create a backup snapshot of the volume being refreshed option is also provided. As previously stated, the option to take the snapshot is enabled by default. The user can disable it, and they can customize the name of the snapshot being taken.

Figure 40.    Refresh Using Related Volume

Figure 41 shows the drop-down option expanded, and the volumes available as a source of the refresh operation for Snap 1 Thin Clone. In this resource family, Snap 1 Thin Clone can be refreshed using the data from the parent resource, Storage Resource, or another thin clone, Snap 2 Thin Clone. If Snap 1 Thin Clone is used for backups or a test or development environment, Refresh can be used to quickly update the contents of the resource to provide the latest information to the user or application. After selecting the source resource for the refresh operation and clicking Refresh, a confirmation window appears. To complete the operation, click Refresh.

Figure 41.    Refresh Using Related Volume

To refresh a volume or volume group thin clone from a supported snapshot, select the snapshot from the Snapshot tab within the Protection tab, click More Actions, then Refresh Using Snapshot. A window similar to the one shown in Figure 40 appears and allows the user to select a volume or volume group thin clone to refresh. Once complete, the resource contains the data that is found within the snapshot.

In PowerStoreOS 3.0 and later, a volume or volume groups’ topology can be viewed. The topology gives a graphical representation of the resource family, along with the parent object and any snapshots and thin clones. Depending on the resource selected in the view, details about the resource, capacity information, and any mapped hosts are also displayed. To view the topology of a resource, navigate to either the Volumes or Volume Groups page, select either a volume, volume group, or a thin clone, then click More Actions > View Topology. An example of the View Topology page can be found below, which is a representation of the storage resource family example found in Figure 39.

Figure 42.    View Topology page

In PowerStoreOS 3.0 and later, you can view a volume or volume groups’ thin clone hierarchy. Within the properties of a thin clone, information regarding the Family, Parent, Source, and Create/Refresh Time is shown (Figure 43). The Family lists the base storage object for all related clones and snapshots. The Parent lists the object from which the clone was created. The Source lists the source of the data for either the creation of the clone or the resource that was the source of the latest refresh. The Create/Refresh Time lists the time the clone was created or last refreshed.

Figure 43.    Create thin clone of a volume example