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

About TrueCopy for z/OS Operations 2-39
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Suspended TrueCopy for z/OS Async Pairs
TrueCopy for z/OS Async operations involve additional suspension conditions
related to the asynchronous recordset operations. Both the MCU and RCU can
detect TCzA suspension conditions and suspend TCzA pairs. Table 2-8describes
the TCzA suspension conditions and indicates which CU detects the condition
and which pairs are suspended. The TCzA offloading timer async option and
timeout group options are used to control the TCzA suspension conditions. See
Table 8-4 for troubleshooting information for TCzA suspension conditions.
Table 2-8 TrueCopy for z/OS Async Suspension Conditions
Suspension Condition Detected
by:
TCzA Pairs to be Suspended
The MCU could not send a pending recordset to the RCU before the
offloading timer async option expired.
MCU All TCzA pairs with M-VOLs in
the MCU.
During MCU power-on, the MCU could not establish communication
with the RCU before the RCU Ready timeout group option expired.
MCU All TCzA pairs with M-VOLs in
the MCU.
The RCU could not settle a pending recordset before the copy
pending timeout group option expired.
RCU All TCzA R-VOLs in the
consistency group.
The RCU could not communicate with the MCU before the copy
pending timeout group option expired.
RCU All TCzA R-VOLs in the
consistency group.
The RCU could not receive the recordset successfully due to a
hardware failure.
RCU Only the affected R-VOL.
The RCU detected a logical error while selecting the recordset to be
settled.
RCU
The RCU could not settle the recordset due to a hardware failure, a
track condition, or a logical error.
RCU
All TCzA R-VOLs in the group,
or only the affected R-VOL,
depending on the failure type
and error level TCzA pair
option.
The MCU stores a differential data in the shared memory for each TCzA M-
VOL, and the RCU stores a differential data in the shared memory for each
TCzA R-VOL. When a TCzA pair is suspended, the tracks which contain the
following records are marked in the differential data as modified (to be copied
during the resynchronize pair operation):
• The recordsets that were created by the MCU but not yet sent to the RCU.
After marking these tracks as modified, the MCU discards these recordsets.
• The recordsets that were sent to the RCU but not acknowledged by the RCU.
The MCU marks these M-VOL tracks as modified and discards these
recordsets. This ensures that recordsets which are lost during transmission to
the RCU are identified and marked.
• The recordsets that reached the RCU but have not yet been settled. After
marking these tracks as modified, the RCU discards these recordsets.