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Chapter 1. Introducing the IBM TotalStorage DS6000 series 11
Incremental FlashCopy
Incremental FlashCopy provides the capability to refresh a LUN or volume involved in a
FlashCopy relationship. When a subsequent FlashCopy is initiated, only the data required to
bring the target current to the source's newly established point-in-time is copied. This
unburdens the backend and the disk drives are not so busy and can do more production I/Os.
The direction of the refresh can also be reversed, in which case the LUN or volume previously
defined as the target becomes the source for the LUN or volume previously defined as the
source (and now the target).
FlashCopy to a remote mirror primary
When we mention remote mirror primary, we mean any primary volume of a Metro Mirror or
Global Copy pair. FlashCopy to a remote mirror primary lets you establish a FlashCopy
relationship where the target is a remote mirror primary volume. This enables you to create
full or incremental point-in-time copies at a local site and let remote mirroring operations copy
the data to the remote site. Many clients that utilize a remote copy function use it for all their
volumes. The DS6800 allows a FlashCopy onto a remote mirror primary volume.
Previous ESS clients faced the issue that they could not use FlashCopy since a FlashCopy
onto a volume that was mirrored was not possible. This restriction particularly affected z/OS
clients using data set level FlashCopy for copy operations within a mirrored pool of production
volumes.
Consistency Group commands
The Consistency Group function of FlashCopy allows the DS6800 to hold off I/O activity to a
LUN or volume until all LUNs/volumes within the group have established a FlashCopy
relationship to their targets and the FlashCopy Consistency Group Created command is
issued or a timer expires. Consistency Groups can be used to help create a consistent
point-in-time copy across multiple LUNs or volumes, and even across multiple DS6800
systems, as well as across DS8000 series, ESS 800, and ESS 750 systems.
Inband commands over remote mirror link
In a remote mirror environment where you want to do a FlashCopy of the remote volumes,
instead of sending FlashCopy commands across an Ethernet connection to the remote
DS6800, Inband FlashCopy allows commands to be issued from the local or intermediate
site, and transmitted over the remote mirror Fibre Channel links for execution on the remote
DS6800. This eliminates the need for a network connection to the remote site solely for the
management of FlashCopy.
Remote Mirror and Copy feature
Remote Mirror and Copy is another separately orderable priced feature; it includes Metro
Mirror, Global Copy, and Global Mirror. The local and remote storage systems must have a
Fibre Channel connection between them. Remote Mirror and Copy functions can also be
established between DS6800 and ESS 800/750 systems, but not between a DS6800 and
older ESS models like the F20, because these models do not support remote mirror or copy
across Fibre Channel (they only support ESCON®) and the DS6800 does not support
ESCON.
Metro Mirror
Metro Mirror was previously called Synchronous Peer-to-Peer Remote Copy (PPRC) on the
ESS. It provides a synchronous copy of LUNs or zSeries CKD volumes. A write I/O to the
source volume is not complete until it is acknowledged by the remote system. Metro Mirror
supports distances of up to 300km.