Hitachi ShadowImage for z/OS user guide (HIT9503-96004, June 2006)

96 ShadowImage for the XP1024/XP128/XP12000/XP10000
Overview of Compatible Mirroring for IBM FlashCopy Version2
The FlashCopy Mirror Version 2 function provides a fast data replication capability. This function allows
you to copy the source data to a targeted volume virtually or physically. Creating the pair by FlashCopy
Mirror Version 2 is called “establishing relationship”. Once a FlashCopy Mirror Version 2 pair is created,
hosts can access data that is copied to the targeted volume.
When you want to copy the data according to dataset, you specify the copy range, then the FlashCopy
Mirror Version 2 creates a pair of only the specified dataset. The copy range is called the “extent”. The
smallest unit used to measure the extent is called the “track”. When the copy source extent and the copy
target extent are in the different volumes, the volume that contains the copy source extent is called an
S-VOL, and the volume that contains the copy target extent is called a T-VOL.
FlashCopy Mirror Version 2 allows you to create up to 16 pairs from one extent. The copy source extent
and copy target extents may co-exist in the same volume. The figure below illustrates the examples of
FlashCopy Mirror Version 2 pairs.
Figure 46 Examples of FlashCopy Mirror Version 2 Pairs Created Between Extents
The extent that is already set as the copy target cannot be used as a copy source extent to create a new
FlashCopy Mirror Version 2 pair. In other words, you cannot create a cascaded FlashCopy Mirror Version
2 pairs. See Figure 47 for the example.
Figure 47 Example of the Case FlashCopy Mirror Version 2 Pair Cannot be Created
Table 44 shows the requirements for using FlashCopy Mirror Version 2.
Table 44 Requirements for FlashCopy Mirror Version 2
Item Requirement
Controller emulation type I-2105
Available volume FlashCopy Mirror Version 2 can use the volume
whose CU:LDEV (control unit image: logical
device ID) is between 00:00 and 3F:FF.