Snapshot
Snapshot is a session type that creates a point-in-time copy of a volume or set of volumes. You do not have to define a specific target volume. The target volumes of a Snapshot session are automatically created when the snapshot is created.
A FlashSystem/IBM Spectrum® Virtualize/IBM Spectrum Accelerate uses a snapshot session to create a large number of volume copies without affecting system performance. By using the snapshot function to create a point-in-time copy, and to manage the copy, you can save storage. With the FlashSystem/IBM Spectrum Virtualize/IBM Spectrum Accelerate snapshots, no storage capacity is used by the snapshot until the source volume or the snapshot is changed.
Figure 1 illustrates a Snapshot session.
TVT Instructions: This graphic was updated for Copy Services Manager 6.2.1, frg_i_snapshot_v2.jpg. To capture this graphic from the Copy Services Manager GUI, click Sessions in the navigation tree > Click Create Session > In the Create Session window, select XIV in the Choose Hardware Type list > In the Choose Session Type list, select Snapshot.
Example
Jane's host applications are using a FlashSystem/IBM Spectrum Virtualize for their back-end storage. With the FlashSystem/IBM Spectrum Virtualize, Jane can create a large number of point-in-time copies of the data. The snapshot function ensures that if data becomes corrupted, she can restore the data to any point in time.
Jane sets up a Snapshot session by using Copy Services Manager and specifies the volume group on the FlashSystem/IBM Spectrum Virtualize system that contains the volume that is used by the host applications. Jane does not have to provision target volumes for all the snapshots she intends to make. She can quickly configure a single Snapshot session.
When the session is configured, Jane creates a Scheduled Task that issues the Create Snapshot command to the session every two hours. If a problem occurs, such as data becoming corrupted, Jane can find a snapshot of the data from a time before the problem occurred. She can restore the data to that point. Jane also sets the Retention option in the Snapshot session properties to three days. Every snapshot that is created will automatically be deleted from the system after three days.
By creating thin clones of snapshots of the data, Jane can also schedule batch processing against that data every day. She can use the batch processing to analyze certain trends in the market without affecting the host applications.