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

7-6 TrueCopy for z/OS Usage Scenarios
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Transferring Sense Information Between Sites
When the MCU (or RCU for TCzA) suspends a TCz pair due to an error
condition, the MCU/RCU sends sense information with unit check status to the
appropriate host(s). This sense information is used during disaster recovery to
determine the currency of the R-VOL. If the host system does not support IBM
PPRC, you must transfer the sense information to the remote site via the error
reporting communications (ERC). If the host system supports IBM PPRC and
receives PPRC-compatible sense information related to a TCz pair, the host OS
will:
1. Temporarily suspend all application I/O operations to the M-VOL.
2. Enter an IEA491E message in the system log (SYSLOG) which indicates the
time that the M-VOL was suspended. Make sure that the system log is
common to both the main and remote OSs.
3. Place specific information about the failure (SIM) in the SYS1.LOGREC
dataset for use by service personnel.
4. Wait for the IEA491E message to reach the remote system.
5. Resume all host application I/O operations to the M-VOL. If the M-VOL fence
level setting does not allow subsequent updates, the MCU will return a unit
check for all subsequent write I/O operations, and the application will
terminate.
Note: Make sure that the MCUs and RCUs are configured to report the service-
level SIMs to the host. Select the Service SIM of Remote Copy = Report
setting on the RCU Option dialog box.