HP XP P9500 Storage - Manual (Page 26)

To determine the number of cylinders
Use the following formula:
The number of cylinders = (ceil ( (ceil (Max. LBA/512) ) /15) ) + 1
where LBA = Logical Block Address
To calculate the number of required bitmap areas
Use the following formula
Required number of bitmap areas = (ceil((number of cylinders x 15)
122,752) )
where:
“number of cylinders x 15” indicates the number of slots
122,752 = the number of slots that a bitmap area can manage
NOTE: If using LUSE volumes, add 1 to the required number of bitmap areas calculated in the
formula above.
To calculate the maximum number of pairs that can be created
The maximum number of pairs you can create is defined by the following:
•
The number of LDEVs in the storage system
Table 2 The relationship between installed additional shared memory and the total number of
LDEVs in the storage system
Total number of LDEVs in storage system Installed additional shared memory for Cnt Ac-J
16,384 Base(16KLDEV,SI/VM)
65,280 64KLDEV,SI/VM Extension1,FCV2,DP,Snapshot,TPF
•
The number of bitmap areas required to create pairs (determined above)
•
The number of bitmap areas of the storage system is 65,536.
Use the following formulae to calculate the maximum possible number of pairs that can be created,
on the basis of the number of bitmap areas and the required number of bitmap areas you calculated:
Maximum number of pairs = floor( Number of bitmap areas / required
number of bitmap areas )
If the calculated maximum number of pairs exceeds the total number of LDEVs of the storage system
and the total LDEV number is less than 32,768, the total number of LDEVs in the storage system is
the maximum number of pairs that can be created.
The maximum number of pairs is limited to 32,768.
Priority set for initial copy operations and scheduling order
For performing more initial copy operations than the setting value of the Maximum Initial Copy
Activities set on the System Option dialog box, the scheduling order (Priority) can be set for the
initial copy operations to be performed. This section explains the assignment of the scheduling
order of initial copy operations in cases where two sets of multiple initial copy operations are
performed.
An example is described in which 4 data volume pairs are created at the same time in cases where
the setting value of the Maximum Initial Copy Activities is 2. The Priority which is set for the P-VOLs
of data volume pairs is shown in the following table.
26 Planning volumes and systems