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

102 ShadowImage for the XP1024/XP128/XP12000/XP10000
NOTE: When FlashCopy® Mirror Version 2 and TCz share volumes, the results of operations such as
creating pairs will differ according to whether you are using a consistency group or not. For details,
”Combining Compatible Mirroring for IBM® FlashCopy® Version 2 With ShadowImage for z/OS®” on
page 109.
Maximum Number of FlashCopy Mirror Version 2 Pairs
This section describes the maximum number of relations assuming that you do not use the relationship
expansion function. For information about the maximum number of relationships (i.e., maximum number of
pairs) when you use the relationship expansion function, see ”Relationship Expansion”.
FlashCopy Mirror Version 2 can establish up to 32,768 pairs. However, FlashCopy Mirror Version 2 may
not be able to establish up to 32,768 relations depending on the number of resources required for the copy
operation that vary according to the attributes (emulation type, capacity, the size of the data that is copied,
the position of the extent) of the volumes and extents used for establishing the pairs. Furthermore, the total
number of available resources also varies according to the number of CUs. You can use the FlashCopy
Information pane (see Figure 26) to check the number of remaining resources that are currently available.
Check the FlashCopy Information pane when you create a FlashCopy Mirror Version 2 pair.
NOTE: The following software programs share the resources used for copy operation.
• ShadowImage for z/OS
• Business Copy XP
• Auto LUN XP
• Flex Copy XP
• Snapshot XP
The resources used by ShadowImage for z/OS, Business Copy XP, Auto LUN XP, Flex Copy XP, and
Snapshot XP cannot be used for FlashCopy Mirror Version 2. The resources that remain when you exclude
the resources used by ShadowImage for z/OS, Business Copy XP, Auto LUN XP, Snapshot XP, and Flex
Copy XP from the total resources are available resources for FlashCopy Mirror Version 2. For details about
the calculation of the resources used by each software program, refer to the following manuals.
• HP StorageWorks Business Copy XP User Guide for the specific disk array
• HP StorageWorks Auto LUN XP User Guide for the specific disk array
• HP StorageWorks Flex Copy XP User Guide
• HP StorageWorks Snapshot XP User Guide
For details about ShadowImage for Mainframe, see
”Requirements on the Maximum Number of Pairs” on
page 16
.
• Creating pairs by volume copying
Use the following expression to calculate the total number of the differential tables per pair:
Total number of the differential tables per pair = ( (X) + (Y) ) x 15 ÷ (Z)
(X): Number of the cylinders of the volume that is divided at arbitrary size.
(Y): Number of the control cylinders (see Table 3).
(Z): Number of slots that can be managed by a differential table.
(1,916 x 32)