Keep the following considerations in mind when creating ShadowImage for Mainframe pairs:
- The P-VOL and S-VOL must be the same size.
- Caution: You can copy an encrypted volume to an unencrypted volume. There is no guard logic to enforce copying encrypted P-VOLs only to encrypted S-VOLs. Unless there is a specific reason for the data to become unencrypted, make sure you maintain the encryption by using encrypted S-VOLs.
- If you are concerned with host I/O performance, make sure that the I/O load is light before creating pairs.
- (VSP One Block 85) If you create a ShadowImage for Mainframe pair during Write Same or Unmap command processing, the pair create operation might fail. In this case, wait until the Write Same or Unmap command processing finishes and then create the pair.
- For initial copy, the maximum copying multiplicity (the number of jobs used for concurrent copy processing) for each pair is 48, but the number might change to 1 if you specify the -split option for the paircreate command. As the result, copy processing might take longer than when the -split option is not specified. Additionally, if you enable the Quick/Steady Split Multiplexing local replica option, the maximum copying multiplicity is 48 even when the -split option is specified.