HP StorageWorks XP Remote Web Console Software - Manual (Page 20)

◦ For OPEN-V:
( ( ( (Max. LBA ч 512) ч 15) ) + 1
The … symbols around a value indicate that the value should be rounded up to the
next integer. The Max. LBA indicates the capacity of a volume and is measured in blocks.
•
The number of bitmap areas:
To calculate the number of bitmap areas in each volume, use the following formulas:
◦ For OPEN-3, OPEN-8, OPEN-9, OPEN-E, OPEN-L, OPEN-K
The number of bitmap areas = ( ((Number of cylinders Ч 15) ч 122,752) )
122,752 is the amount of differential data per bitmap area. The differential data is
measured in bits. If you are managing the differential data by cylinder, use the number
of the cylinders instead of the number which is derived from number of cylinders x 15 to
calculate the number of bitmap areas.
◦ For OPEN-V (when calculating the number of bitmap areas by using the number of
cylinders that is calculated by using the formula mentioned earlier)
The number of bitmap areas = ( ((Number of cylinders Ч 15) ч 122,752) )
◦ For OPEN-V (when calculating the number of bitmap areas by using the number of
cylinders displayed in Remote Web Console windows)
The number of bitmap areas =
( (((Number of cylinders ч 4) Ч 15) ч 122,752) )
The … symbols around a value indicate that the value should be rounded up to the
next integer.
•
The maximum number of pairs that can be created:
The number of bitmap areas you can use in the storage system depends on the number of
shared memories you add to the storage system.
Table 3 (page 20) describes the relationship
between the number of shared memories and the number of usable bitmap areas of the storage
system.
Table 3 Relationship between the Additional Shared Memory and the Number of Usable Bitmap
Areas of the Storage System
Number of Usable Bitmap Areas of the Storage
System Additional Shared Memory for XP Continuous Access
0 No additional shared memory for XP Continuous
Access
7,424 Additional shared memory for XP Continuous Access
is installed
16,384 Extension 1
32,768 Extension 2
44,256 Extension 3 (available for only HP XP24000 Disk
Array)
65,536 Extension 4 (available for only HP XP24000 Disk
Array)
If the calculated number of bitmap areas exceeds the total number of bitmap areas in the
storage system, the number of pairs that can be created will be limited. Note that the maximum
number of pairs that you can create cannot exceed 32,768. However, if the RAID Manager
command device is defined, the maximum number of pairs that you can create cannot exceed
32,767.
20 About XP Continuous Access Operations