The FlashCopy function enables you to make point-in-time, full
volume copies of data, with the copies immediately available for read or write
access. 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
that it takes to complete the background copy 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 DS6000 series
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
- Allows you 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 complete.
- 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
completes. You must explicitly delete the relationship.
- Refresh target volume
- Provides the ability to “refresh” a FlashCopy relationship, without recopying
all tracks from the source volume to the target volume.
- Reverse restore
- Reverses the FlashCopy relationship and copies data from the target volume
to the source volume.