The FlashCopy feature transfers a point-in-time copy of a source volume onto a designated target volume. You must create or already have an existing target volume before you can transfer the copy. You must also ensure that the target volume has enough space available to support the amount of data that is being transferred.
After the mapping is started, all of the data that is stored on the source volume can be accessed through the target volume. This data includes any operating system control information, application data, and metadata that was stored on the source volume. As a result, some operating systems do not allow a source volume and a target volume to be addressable on the same host.
To ensure the integrity of the copy, the host cache of any outstanding reads or writes must be flushed completely before you proceed with the FlashCopy operation. You can flush the host cache by unmounting the source volumes from the source host before you start the FlashCopy operation.
The target volumes are overwritten with a complete image of the source volumes. Before the FlashCopy mappings are started, it is important that any data held on the host operating system (or application) caches for the target volumes is discarded. The easiest way to ensure that no data is held in these caches is to unmount the target volumesbefore the FlashCopy operation starts.
Some operating systems and applications provide facilities to stop I/O operations and ensure that all data is flushed from caches on the host. If these facilities are available, they can be used to prepare and start a FlashCopy operation. See your host and application documentation for details.
Some operating systems are unable to use a copy of a volume without synthesis. Synthesis transforms the operating system metadata on the target volume to enable the operating system to use the disk. Refer to your host documentation on how to detect and mount the copied volumes.