Creating a Snapshot Set

A snapshot is a persistent image of a source virtual volume at a particular point in time. The relationship between the source virtual volume and the destination virtual volume that contains the snapshot is called a snapshot set (or relationship).  Each snapshot set created is assigned a unique relationship number.

For instructions on the step-by-step Snapshot process, see Getting Started with Snapshot.

Before beginning:

  • Refer to Supported Snapshot Set Configurations for valid Snapshot configurations.

  • Snapshot sets with a dynamic source and static destination are not allowed without enabling the Allow Static Destination with Dynamic Source check box (see step 7 below). See Allow Mixed Static and Dynamic Mirrors.

Suggestions for optimal storage allocation and performance:

  • Use dynamic volumes for source and destination in a set to allow for performance optimization.

  • Create Snapshot relationships using destination virtual volumes from a dedicated NMV pool configured with the smallest SAU size (1 MB).  Doing this will allow for the optimal storage allocation on the destination.

  • Impact of Snapshot I/O on performance will be minimized by placing the destination virtual volumes on faster physical disks.

  • I/O to destinations that are not Complete Images (CI) increase the I/O load on the Snapshot source. This I/O can impact performance. Consider performing a CI to limit the impact.

Follow these steps to create a snapshot set:

  1. Open the Snapshot Manager snap-in.

  2. Right-click SnapshotSets and choose New Snapshot Set.

    SANmelody create snapshot1 Creating a Snapshot Set

  3. First, assign the snapshot source:

    1. In the Create Snapshot Set dialog box, select one or more virtual volumes from the list in the top pane to be the sources of snapshot sets and click the green down arrow. The virtual volumes will appear in the lower pane.
       

      SANmelody create snapshot2 Creating a Snapshot Set SANmelody create snapshot3 Creating a Snapshot Set

    2. Click OK to complete your selection and close the dialog box. In the upper pane of Snapshot Manager, notice that snapshot names and relationship numbers are assigned to the partial snapshot sets.

  4. Next, assign the snapshot destination:

    1. In the upper pane, select a newly created snapshot set (source) and choose Set Destination from the shortcut menu.
      SANmelody create snapshot4 Creating a Snapshot Set

    2. In the Set Destination dialog box, select a virtual volume from the list of candidates to be the snapshot destination.
      SANmelody create snapshot5 Creating a Snapshot Set

    3. In special cases, it may be necessary to use a dynamic source virtual volume with a static (standard protected) destination virtual volume. Refer to Allow Mixed Static and Dynamic Mirrors before enabling the Allow Static Destination with Dynamic Source check box. After selecting this check box, additional destination candidates will appear in the list.

    4. Click OK after making your selection. Notice in the view below the two virtual volumes that comprise Snapshot1 are listed in the lower pane. The snapshot is disabled until the enable command is performed.
      SANmelody create snapshot6 Creating a Snapshot Set

    5. Repeat the steps above to select snapshot destinations for all the sets created.

  5. Apply the configuration changes.

 

To remove a source or destination volume from a snapshot set:

Select the snapshot set in the upper-right pane, select the source or destination in the lower-right pane and choose Delete. If you remove the source volume, the snapshot set is removed.

To modify or delete a snapshot set:  

See Modifying a Snapshot Set or Deleting a Snapshot Set.

Creating a Snapshot Set