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

Performing TrueCopy for z/OS Configuration Operations 5-13
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Changing the RCU Options
The RCU Option dialog box (see Figure 5-3) allows you to set the RCU options
for the connected MCU. The RCU options apply to all MCU CUs and to all RCUs
connected to the MCU. The RCU Option dialog box is presented during the add
RCU process, and can also be opened by right-clicking on the RCUs and
clicking the RCU OperationÆChange RCU Option command.
Figure 5-3 RCU Option Dialog Box
The Minimum Paths option allows you to specify the minimum number of
paths required for each RCU connected to the current MCU (default = 1). If
you enter a larger number than the number of paths already set on the Add
RCU dialog box, or if the number of paths falls below this number (e.g., failed
path), an error occurs. When the error occurs, the MCU suspends all affected
TrueCopy for z/OS (and TrueCopy) pairs to prevent remote copy operations
from adversely affecting performance due to the inadequate number of paths.
If the MCU contains TrueCopy for z/OS pairs which contain critical data for
disaster recovery, set the minimum number of paths to one, so that TrueCopy
for z/OS operations continue even if there is only one path to an RCU. If you
need high performance at the MCU, set the minimum number of paths to two
or more (up to eight per CU), depending on the number of pairs managed by
the MCU.
Note: When you have TrueCopy for z/OS Async pairs configured on fibre-
channel interface, set the same value for the Minimum Paths option for all
RCUs.
Note: The RCU options are common to both TrueCopy for z/OS and TrueCopy
operations. The most recently entered Minimum Paths value (entered on
TrueCopy for z/OS or TrueCopy RCU Option dialog box) will be applied to both
TrueCopy for z/OS and TrueCopy operations.