Calculating The Maximum Number Of Pairs; S-Vol Resource Group And Storage System: Same Serial Number And Model; Calculating The Number Of Available Bitmap Areas - Hitachi G1000 User Manual

• Calculating the number of cylinders on page 3-17
• Calculating the number of available bitmap areas on page 3-18

Calculating the number of available bitmap areas

The total number of bitmap areas available in the storage system is 65,536.
The number of bitmap areas is shared by TrueCopy, TrueCopy for Mainframe,
Universal Replicator, and Hitachi Universal Replicator for Mainframe. If you
use these software products, subtract the number of bitmap areas required
for these products from the total number of bitmap areas in the storage
system (65,536), and then use the formula in the next section to calculate
the maximum number of GAD pairs. For details on the methods for
calculating the number of bitmap areas required for these program products,
refer to the appropriate user guide.

Calculating the maximum number of pairs

Use the following values to calculate the maximum number of pairs:
• The number of bitmap areas required for pair creation
• The total number of bitmap areas available in the storage system (that is,
65,536), or the number of available bitmap areas calculated in the
previous section
Calculate the maximum number of pairs using the following formula with
the total number of bitmap areas in the storage system (or the number of
available bitmap areas) and the number of required bitmap areas, as
follows:
maximum-number-of-pairs-that-can-be-created = floor(total-
number-of-bitmap-areas-in-storage-system / number-of-required-
bitmap-areas)
Related topics
• Maximum number of GAD pairs on page 3-16
• Calculating the number of available bitmap areas on page 3-18
S-VOL resource group and storage system: same serial number and
model
You can create GAD pairs specifying a volume in a resource group that has
the same serial number and model as the storage system for the S-VOL. In
this case, you must specify a volume in the resource group (virtual storage
machine) whose serial number and model are same as the secondary storage
system for the P-VOL.
When you create GAD pairs, the virtual LDEV ID of the P-VOL is copied to the
virtual LDEV ID of the S-VOL. In the following figure, the copied virtual LDEV
ID of the P-VOL is equal to the original virtual LDEV ID of the S-VOL. The
volume in a resource group that has the same serial number and the same
model as the storage system and whose original LDEV ID is equal to the
3-18
Hitachi Virtual Storage Platform G1000 Global-Active Device User Guide
Planning for global-active device