Precautions for duplicate VOLSERs

For the TrueCopy for Mainframe initial copy operation, the P-VOL VOLSER (volume serial number) is also copied to the S-VOL when the -copy_mode none option is not specified in the raidcom add remote_copy_pair command. Therefore, the P-VOL and S-VOL have the same VOLSER. The host operating system does not allow duplicate VOLSERs, so you must take precautions, such as defining S-VOLs so they do not come online automatically, to prevent system problems related to duplicate VOLSERs.

If the S-VOLs are physically attached to the same system images as the P-VOLs, the following possible error conditions can occur:

• If the secondary system is online when a pair is established using the CESTPAIR command (allowed by PPRC, not allowed by TCz), a duplex secondary could be online to a host image. The results of this situation are not predictable.
• When a pair is released, the volume that was the S-VOL is usually offline. Later, when the host IPL is performed, the operator is offered both volumes and asked which volume should be left offline. You can avoid duplication of the VOLSER as follows:
  1. Identify the volumes that are not accessed by the host system.
  2. Perform CHP OFF or some other operation to ensure that the volumes are inaccessible.
  3. When performing IPL, make sure to perform LOAD CLEAR.

To avoid these possible error conditions:

• Specify OFFLINE=YES if the S-VOLs will be generated in the production host's IOCP and system generation.
• If you cannot create a pair because the S-VOL is online with hosts, all paths must be offline from all hosts.