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

About TrueCopy for z/OS Operations 2-29
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Time Out [Copy Pending]. This group option specifies the maximum delay
allowed for TCzA copy operations.
WARNING: See Adding Consistency Groups
for instructions on selecting the
correct Time Out [Copy Pending] setting for your operational environment.
The RCU will suspend all R-VOLs in the group when:
• The RCU has not had any communication from the MCU within the specified
time. This situation could indicate a disaster or failure at the primary site.
• The RCU has been receiving recordsets from the MCU(s) but has not been
able to settle a recordset within the specified time. This situation may
indicate that the RCU does not have enough resources to handle the remote
copy and I/O workloads.
RCU Ready. This option specifies the maximum delay for re-establishing MCU-
RCU communications following MCU power-off. During MCU power-on, the
MCU re-establishes communication with all registered RCUs. If it is not able to
re-establish communication with an RCU within the specified time, the MCU
suspends all affected TCzA pairs.
Group Consistency Time
During normal TCzA operations, the consistency time (C/T) of a group
corresponds to the time-stamp value of the most recently settled recordset at
the RCU. The consistency time for the group is indicated as part of the TCzA R-
VOL pair status (also displayed by the CQUERY TSO command to the R-VOL).
As the main system continues to update the TCzA M-VOLs, the difference
between the current system time and the group consistency time indicates the
amount of time that the R-VOLs are behind the M-VOLs. The M-VOL updates
which take place during this time may be lost when a disaster occurs.
When a TCzA pair is suspended, the C/T of the suspended R-VOL is frozen. If
the RCU can ensure the update sequence consistency between the suspended
R-VOL and the other R-VOLs in the consistency group, the R-VOL C/T is frozen
at the latest consistency time of the group. Otherwise, the R-VOL C/T is frozen
at the time-stamp value of the most recent update that was successfully
copied to the R-VOL. The C/T of a suspended R-VOL may be older than the C/T
of other R-VOLs in the group, and if the entire group was not also suspended,
the consistency time of the group is still ticking. For suspended TCzA R-VOLs,
the TCz Detailed Information dialog box displays whether the C/T was frozen
to the group or R-VOL time.