Hitachi G200 - Hitachi Truecopy; System Components

Hitachi TrueCopy®
Hitachi TrueCopy® (TC) provides a continuous, nondisruptive, host-
independent remote data-replication solution for disaster recovery or data
migration purposes. Using the TrueCopy Remote Replication software, you
can create and maintain mirror images of production volumes at a remote
location. TrueCopy Remote Replication software can be deployed with Hitachi
Universal Replicator software's asynchronous replication capabilities to
provide advanced data replication among multiple data centers. In addition,
TrueCopy Remote Replication software can be integrated with Hitachi
ShadowImage® Replication software to enable robust business-continuity
solutions. This lets you create a remote copy of primary site or production
data that is automatically updated for executing test and development tasks,
or for operations against production data.
The TrueCopy primary storage system contains the primary volume (P-VOL)
of a copy pair, and the secondary storage system contains the secondary
volume (S-VOL). When the primary storage system accepts a write operation
for a P-VOL, the data is written on the primary volume and then sent by the
primary storage system to the secondary storage system through the
dedicated data paths connecting the storage systems. Subsequent write
operations are not accepted by the primary volume until acknowledgement is
received from the secondary storage system for the previous write operation,
ensuring that the data in the secondary volume stays synchronized with the
primary volume.
To reduce the overhead associated with these remote copy activities and
maximize data transfer, the primary storage system uses a special write
command for TrueCopy remote 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. The special write command
eliminates the overhead required for performing FBA-to-CKD and CKD-to-FBA
conversions.
TrueCopy operations can be performed using the TrueCopy Remote
Replication software and the Command Control Interface software (CCI)
command-line interface software. This document describes and provides
instructions for performing TrueCopy operations using the TrueCopy software
on Device Manager - Storage Navigator. For details about using CCI to
perform TrueCopy operations, see the user documentation for CCI.
System components
TrueCopy operations involve the storage systems and volumes at the primary
site and secondary (remote) site, the physical communications paths between
these storage systems, and the TrueCopy software. A TrueCopy system
configuration consists of the following components:
• Primary and secondary storage systems. The primary storage system
contains the primary volumes and is connected to the hosts that access
the primary volumes. The secondary storage system is connected to the
primary storage system using dedicated data paths. TrueCopy supports
1-2
TrueCopy overview
Hitachi TrueCopy® User Guide for Hitachi Virtual Storage Platform Gx00 and Fx00 Models