Calculating Maximum Number Of Pairs - HP XP P9500 User Manual

Round up the total number to the nearest whole number. For example, if the number of the cylinders
of the divided volume is 3,019,898,880 KB, the calculation of the total number of the differential
tables is as follows.
(3,019,898,880 ÷ 256) ÷ 20,448 = 576.9014...
When you round up 576.9014 to the nearest whole number, it becomes 577. In this example,
the total number of the differential tables for one pair is 577. Because one pair table is used for
up to 36 differential tables, the total number of the pair tables for a pair is 17. (Only OPEN-V can
use more than one pair table per pair.)
Table 4 Control cylinders per emulation type
Emulation type
OPEN-3
OPEN-8, OPEN-9
OPEN-E
OPEN-K
OPEN-L
OPEN-V
If the volume is divided by VLL, use the volume capacity after the division. Note that VLL operations
cannot be performed on OPEN-L volumes.
Having determined the number of differential and pair tables required per pair on your storage
system, you can now calculate the maximum number of pairs.

Calculating maximum number of pairs

Finding the number of pairs which can be created on your system depends on whether you use
LUSE volumes or not. Two calculations are provided below, one without LUSE, and one with LUSE.
To calculate the maximum number of pairs allowed on your system without LUSE volumes
Use the following formula:
Σ {(α) x (the number of Business Copy pairs)} ≤ (β) and Σ {(γ) x (the number of Business Copy
pairs)} ≤ (δ)
where:
(α): Required number of differential tables per pair (per previous calculation).
(β): Number of differential tables available in the system
(γ): The required number of pair tables per pair (per previous calculation).
(δ): The number of pair tables available in the system
For example, if you are to create 10 pairs of OPEN-3 volumes and 20 pairs of OPEN-V volumes
in a storage system that has 26,176 differential tables, you can use the equation as follows:
When the emulation type is OPEN-3, and if the capacity of the volume is 2,403,360 kB, the
number of differential tables required for a pair will be 3, and the number of pair tables required
for a pair will be 1. When the emulation type is OPEN-V, and if the capacity of the volume is
3,019,898,880 kB, the number of differential tables required for a pair will be 577, and the
number of pair tables required for a pair will be 17.
If you apply these numbers in equation:
3 x 10 + 577 x 20 = 1 1,570 less-than-or-equal-to 26,167 and also
1 x 10 + 17 x 20 = 350 less-than-or-equal-to 8,192
Thus, 10 pairs of OPEN-3 volumes and 20 pairs of OPEN V volumes can be created.
14 Requirements and planning
Number of control cylinders
8 (5,760KB)
27 (19,440KB)
19 (13,680KB)
9 (6,480KB)
7 (5,040KB)
0 (0KB)
(Table 3 (page
(Table 3 (page
13)).
13)).