Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

2-30 About TrueCopy for z/OS Operations
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Once you have established TCzA operations, you should monitor the
consistency time of each group at the RCU(s). If the average delay is longer
than your disaster recovery design can accept, you should consider adding
remote copy resources (e.g., paths, cache) and/or reducing the I/O workload
to improve storage system performance. If the delay between the M-VOL
update and the corresponding R-VOL update reaches the time specified by the
Time Out [Copy Pending] group option, the MCU will suspend all affected
pair(s) due to the heavy I/O workload (at MCU or RCU). To prevent timeout
errors, you can increase the Time Out [Copy Pending] value, reduce I/O
workload, and/or add remote copy resources.
Note: This information is valid only when the timer type is System.