Special considerations

When you combine the volume copy function with the volume dump function, you must give consideration to how you will use the following keywords:

DUMPCONDITIONING
FCNOCOPY
FCWITHDRAW

These keywords are described in the sections that follow.

DUMPCONDITIONING — Allows you to make a copy of the source volume in a full volume copy operation—including volume index information—while keeping the target volume online. Use this keyword when you want to create a copy of the source volume for backup purposes, rather than to allow applications to use the target volume.

With DUMPCONDITIONING in effect, the volume serial number of the target volume does not change, and the target volume remains online after the copy. The VVDS and VTOC index names on the target volume do not change to match the target volume serial number; they continue to match the source volume serial number.

In Step 2 , for example, you can include the DUMPCONDITIONING keyword on the full volume copy command to allow the target volume to remain online for dumping.

The target of a full volume copy operation using DUMPCONDITIONING is referred to as a conditioned volume. A full volume dump of a conditioned volume appears as if it were dumped from the original source volume of the copy operation. However, if the conditioned volume is copied back using DUMPCONDITIONING, conditioning is not performed on the original source volume. Instead, DFSMSdss recognizes that it is copying from the target of a previous conditioned-backup and recovers the original source volume.

For example, suppose that you specify the DUMPCONDITIONING keyword when you perform a full volume copy of volume VOL001 to volume VOL002. If you then perform a full volume dump of VOL002 to tape, the output appears as if you had dumped VOL001 directly. Now suppose that you copy VOL002 back to VOL001. Here, the VOL002 volume serial number is not copied to VOL001's volume label, because DFSMSdss treats VOL002 as a copy of VOL001.

This example assumes that the source volume VOL001 has an indexed VTOC. If the source volume does not have an indexed VTOC, a full volume dump of the conditioned volume VOL002 would not look as if it was dumped from the original source volume VOL001. Rather, it would be an exact image of the conditioned volume. A subsequent full volume restore with the COPYVOLID keyword specified results in the target volume having the same serial number as the conditioned volume.

FCNOCOPY/FCWITHDRAW — Using these two keywords in your procedure is recommended when you use FlashCopy®.

You can specify the FCNOCOPY keyword on the COPY command to prevent the ESS subsystem from performing a full physical copy of the volume. Doing so can save subsystem resources and can help to avoid affecting the performance of other I/O operations done by the ESS subsystem.
You can specify the FCWITHDRAW keyword on the DUMP command to cause DFSMSdss to withdraw the FlashCopy relationship after the volume has been successfully dumped. Doing so frees the subsystem resources that are used to maintain the FlashCopy relationship.

During DUMP FULL and DUMP TRACKS operations, DFSMSdss invokes ICKDSF to initialize the source volume of the DUMP operation at the end of dump processing, when all of the following conditions are true:

FCWITHDRAW is specified
The VTOC tracks on the source volume of the DUMP operation are the target of a FlashCopy relationship
If TRACKS is specified, it designates one extent range that represents the entire volume
The volume is not a VM-format volume (CP volume)
The volume supports data set FlashCopy or space efficient FlashCopy.

Note: If you perform a dump operation with FCWITHDRAW specified, and the dump source volume is shared between multiple systems, ensure that the DASD is offline to all systems except the one performing the dump.

Timing is an important factor in the successful use of these keywords. In your procedure, allow only a short amount of time to elapse between the completion of step 2 (copy function) and the start of step 4 (backup function). Here, you can specify the FCNOCOPY keyword in step 2 and the FCWITHDRAW keyword in step 4.

Do not use the FCNOCOPY and FCWITHDRAW keywords if the backup (step 4) will not be performed within a reasonable amount of time after the copy (step 2). Otherwise, the use of FlashCopy consumes the subsystem resources for an extended amount of time.