IBM DS6000 Series manual Remote Mirror and Copy feature

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.

Chapter 1. Introducing the IBM TotalStorage DS6000 series 11