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Chapter 2 Overview of CCI Operations
2.4
Hitachi TrueCopy/ShadowImage Volumes
Hitachi TrueCopy commands allow you to create volume pairs consisting of one primary
volume (P-VOL) and one secondary volume (S-VOL). The TrueCopy P-VOL and S-VOL can be in
different storage systems. Hitachi TrueCopy provides synchronous and asynchronous copy
modes. TrueCopy Asynchronous can only be used between separate storage systems (not
within one storage system). The maximum number of TrueCopy pairs in one storage system
is 16,383 for TagmaStore USP/NSC, 8191 for 9900V, and 4095 for 9900, provided that one
LUN is dedicated to the command device. For details on TrueCopy volumes and operations,
please refer to the
Hitachi TrueCopy User and Reference Guide
for the storage system.
ShadowImage commands allow you to create volume pairs consisting of one P-VOL and up to
nine S-VOLs using the ShadowImage cascade function. ShadowImage pairs are contained
within the same storage system and are maintained using asynchronous update copy
operations. The maximum number of ShadowImage pairs in one storage system is 8191 for
TagmaStore USP/NSC, 4095 for 9900V, and 2047 for 9900. For details on ShadowImage
volumes and operations, please refer to the
Hitachi ShadowImage User’s Guide
for the
storage system.
Each volume pair that you want to create must be registered in the CCI configuration file.
ShadowImage volume pairs must include an MU (mirrored unit) number assigned to the
S-VOL. The MU number indicates that the pair is a ShadowImage pair and not a Hitachi
TrueCopy pair. Once the correspondence between the paired logical volumes has been
defined in the HORCM_DEV section of the configuration file, you can use the configuration
file to group the paired volumes into volume groups that can be managed by the host
operating system’s LVM (logical volume manager).
The host’s LVM allows you to manage the Hitachi TrueCopy/ShadowImage volumes as
individual volumes or by volume group. TrueCopy/ShadowImage commands can specify
individual logical volumes or group names. For LUN Expansion (LUSE) volumes, you must
enter commands for each volume (LDEV) within the expanded LU. If you define volume
groups and you want to issue commands to those volume groups, you must register the
volume groups in the configuration file. For further information on the LVM, refer to the
user documentation for your operating system.
Summary of Contents for TAGMASTORE MK-90RD011-25
Page 2: ......
Page 8: ...viii Preface ...
Page 18: ...xviii Contents ...
Page 180: ...162 Chapter 3 Preparing for CCI Operations ...
Page 250: ...232 Chapter 4 Performing CCI Operations Vol Type logical unit LU type e g OPEN V OPEN 9 ...
Page 370: ...352 Chapter 5 Troubleshooting ...
Page 388: ...370 Acronyms and Abbreviations ...