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Hitachi Lightning 9900™ User and Reference Guide 41
3.7.3 Hitachi ShadowImage (SI)
Hitachi ShadowImage enables open-system users to maintain subsystem-internal copies of
LUs for purposes such as data backup or data duplication. The RAID-protected duplicate LUs
(up to nine) are created within the same 9900 subsystem as the primary LU at hardware
speeds. Once established, ShadowImage operations continue unattended to provide
asynchronous internal data backup. ShadowImage operations are nondisruptive; the primary
LU of each ShadowImage pair remains available to all hosts for both read and write
operations during normal operations. Usability is further enhanced through a
resynchronization capability that reduces data duplication requirements and backup time,
thereby increasing user productivity. ShadowImage also supports reverse resynchronization
for maximum flexibility.
ShadowImage operations can be performed in conjunction with Hitachi TrueCopy operations
(see section 3.7.1) to provide multiple copies of critical data at both primary and remote
sites. ShadowImage also supports the Virtual LVI/LUN and FlashAccess features of the 9900
subsystem, ensuring that all user data can be duplicated by ShadowImage operations.
Note: For further information on Hitachi ShadowImage, please see the Hitachi Lightning
9900™ ShadowImage User’s Guide (MK-90RD031), or contact your Hitachi Data Systems
account team.
3.7.4 Hitachi ShadowImage – S/390
®
(SI390)
Hitachi ShadowImage – S/390
®
enables S/390
®
users to create high-performance copies of
source LVIs for testing or modification while benefiting from full RAID protection for the
ShadowImage copies. The ShadowImage copies can be available to the same or different
logical partitions (LPARs) as the original volumes for read and write I/Os. ShadowImage
allows the user to create up to three copies of a single source LVI and perform updates in
either direction, either from the source LVI to the ShadowImage copy or from the copy back
to the source LVI. When used in conjunction with either TrueCopy – S/390
®
or HXRC,
ShadowImage – S/390
®
enables users to maintain multiple copies of critical data at both
primary and remote sites. ShadowImage also supports the Virtual LVI/LUN and FlashAccess
features, ensuring that all user data can be duplicated by ShadowImage operations
Note: For further information on Hitachi ShadowImage – S/390
®
, please see the Hitachi
Lightning 9900™ ShadowImage – S/390
®
User’s Guide (MK-90RD012), or contact your Hitachi
Data Systems account team.