Hitachi TAGMASTORE MK-90RD011-25 - Manual (Page 27)

Hitachi Command Control Interface (CCI) User and Reference Guide 9
2.2 Features of Paired Volumes
The logical volumes, which have been handled independently by server machines, can be
combined or separated in a pair being handled uniformly by the Hitachi TrueCopy and/or
ShadowImage pairing function. Hitachi TrueCopy and ShadowImage regard those two
volumes to be combined or separated as unique paired logical volume used by the servers. It
is possible to handle paired volumes as groups by grouping them in units of server software
or in units of database and its attribute.
Oradb
Special files
A and B
Server A
Special files
C and D
Server B
Oradb
Group name: oradb
Paired logical volume
Volume A Volume C
Oradb1
Paired logical volume
Volume B Volume D Oradb2
Special files
C and D
Server C
Oradb
Local volume space of server A
Figure 2.1 Concept of Paired Volumes
Addressing paired logical volumes: The correspondences between the paired logical
volumes and physical volumes are defined by users by describing any intended paired logical
volume names and group names in the configuration definition file of each server. It is
possible to define a server for the paired logical volumes in units of group name. Each paired
logical volume must belong to a group in order to determine the corresponding server.
Specification of volumes by commands: Volume names to be specified by the TrueCopy
commands must be given using the paired logical volume names or the group names.