HP StorageWorks XP Remote Web Console Software - Manual (Page 18)

which span multiple volumes, allowing immediate database recovery at the remote site when
needed.
Host I/O Time-Stamping Function
If you plan to establish TrueCopy for Mainframe Asynchronous consistency groups, the I/O
time-stamping function must be installed on the host processor at the main (primary) site. The I/O
time stamp, which is provided by MVS DFSMSdfp, is the same time stamp that is used by XRC
pairs. The RCU requires the I/O time-stamp information to process TrueCopy for Mainframe
Asynchronous recordsets. The I/O time-stamping function should also be installed on the host
processor at the remote (secondary) site, so that time stamps can be used when copying data in
the reverse direction.
If the main and/or remote system consists of several CPU complexes, a SYSPLEX timer is required
to provide a common time reference for the I/O time-stamping function.
Error Reporting Communications
Error reporting communications (ERC), which transfers information between host processors at the
main and remote sites, is a critical component of any disaster recovery effort. You can configure
ERC using channel-to-channel communications, NetView technology, or other interconnect
technologies, depending on your installation requirements and standards. TrueCopy for Mainframe
software does not provide ERC between the main and remote sites.
When TrueCopy for Mainframe is used as a data migration tool, ERC is recommended but is not
required. When TrueCopy for Mainframe is used as a disaster recovery tool, ERC is required to
ensure effective disaster recovery operations. When a TrueCopy for Mainframe pair is suspended
due to an error condition, the MCU generates sense information which results in an IEA491E
system console message. This information should be transferred to the remote site via the ERC for
effective disaster detection and recovery.
Remote Copy Operations
“TrueCopy for Mainframe Remote Copy Operations” (page 18) illustrates the two types of TrueCopy
for Mainframe remote copy operations: initial copy and update copy. To reduce the overhead
associated with these remote copy activities and maximize data transfer, the HP disk array utilizes
a special write command which is allowed only for TrueCopy for Mainframe initial and update
copy operations. This command transfers the control parameters and the FBA-format data for
consecutive updated records in a track using a single write operation.
Figure 2 TrueCopy for Mainframe Remote Copy Operations
This section describes the following aspects of TrueCopy for Mainframe remote copy operations:
•
Initial copy operations
•
Update copy operations
18 About TrueCopy for Mainframe Operations