FlashCopy

You can make point-in-time, full volume copies of data, with the copies immediately available for read or write access with the FlashCopy function. You can use the copy with standard backup tools that are available in your environment to create backup copies on tape.

FlashCopy creates a copy of a source volume on the target volume. This copy is called a point-in-time copy. When you initiate a FlashCopy operation, a FlashCopy relationship is created between a source volume and target volume. A FlashCopy relationship is a "mapping" of the FlashCopy source volume and a FlashCopy target volume. This mapping allows a point-in-time copy of that source volume to be copied to the associated target volume. The FlashCopy relationship exists between this volume pair from the time that you initiate a FlashCopy operation until the storage unit copies all data from the source volume to the target volume or you delete the FlashCopy relationship, if it is a persistent FlashCopy.

When the data is physically copied, a background process copies tracks from the source volume to the target volume. The amount of time the background copy requires to be completed depends on the following criteria:

The amount of data being copied
The number of background copy processes that are occurring
The other activities that are occurring on the DS8000®

Notes:

FlashCopy relationships are supported on thin-provisioning (open system) volumes.
At the data set level, the maximum number of FlashCopy relationships allowed on a volume is 65534. If that number is exceeded, the FlashCopy operation fails.
With full volume FlashCopy, a source volume can be in FlashCopy and FlashCopy Space Efficient relationships with a maximum of 12 target volumes. If that number is exceeded, the FlashCopy operation fails. Of the up to 12 FlashCopy relationships, only one incremental FlashCopy relationship is allowed.
With FlashCopy Space Efficient, a source volume can be in FlashCopy and FlashCopy Space Efficient relationships with a maximum of 12 target volumes. If that number is exceeded, the FlashCopy operation fails.

FlashCopy supports the following copy options:

Consistency groups: Creates a consistent point-in-time copy of multiple volumes, with negligible host impact. You can enable FlashCopy consistency groups from the command-line interface (DS CLI).
Change recording: Activates the change recording function on the volume pair that is participating in a FlashCopy relationship. This enables a subsequent refresh to the target volume.
Establish FlashCopy on existing Metro Mirror source: Provides the ability to establish a FlashCopy relationship where the target volume is also the source of an existing remote mirror and copy source volume. This enables you to create full or incremental point-in-time copies at a local site and then use remote mirroring commands to copy the data to the remote site.
Fast reverse: Reverses the FlashCopy relationship without waiting for the finish of the background copy of the previous FlashCopy. This option applies to the Global Mirror mode.
Inhibit writes to target: Ensures that write operations are inhibited on the target volume until a refresh FlashCopy operation is completed.
Multiple Relationship FlashCopy: Allows a source volume to have multiple target volumes at the same time.
Persistent FlashCopy: Allows the FlashCopy relationship to remain even after the FlashCopy operation is completed. You must explicitly delete the relationship.
Reverse restore: Reverses the FlashCopy relationship and copies data from the target volume to the source volume.