HP StorageWorks XP Remote Web Console Software - Manual (Page 42)

42 Continuous Access XP Journal operations requirements and restrictions
specifies. A limit on the number of pairs is applied to the primary and secondary arrays. Use the
following formula to calculate the number of cylinders for different emulation types:
• For OPEN-V
Number of cylinders = ( ↑ ( ( ↑ (Max. LBA/512) ↑ ) /15) ↑ ) + 1
The ↑ … ↑ symbols around a value indicate the value should be rounded up to the nearest integer.
• Number of bitmap areas:
Calculate the number of bitmap areas to be used by all data volumes forming pairs from the number of
cylinders. If one pair of extended shared memories is used, 11,605 bitmap areas can be used in an
array. If two pairs of extended shared memories are used, 28,671 bitmap areas can be used in an
array.
NOTE: If the calculated number of bitmap areas exceeds the total number of bitmap areas in the
array, the number of pairs you can create is limited.
Use the following formula to calculate the number of bitmap areas to be used for each volume:
Number of bitmap areas = (
↑ ((Number of cylinders × 15) / 122,752) ↑ )
The ↑ … ↑ symbols around a value indicate the value should be rounded up to the nearest integer.
• Maximum number of pairs that can be created:
Use the following formulas to calculate the maximum number of pairs you can create:
• When one pair of extended shared cache memories is used
Maximum number of pairs = ( ↓ (11,605 /Number of bitmap areas) ↓ )
The ↓ … ↓ symbols around a value indicate the value should be rounded down to the nearest
integer.
• When two pairs of extended shared cache memories are used
Maximum number of pairs = ( ↓ (28,671 /Number of bitmap areas) ↓ )
The ↓ … ↓ symbols around a value indicate the value should be rounded down to the nearest
integer.
NOTE: If the calculated maximum number of pairs exceeds 16,384, the actual maximum number
of pairs is limited to 16,384.
NOTE: The capacity of OPEN-V is variable. To calculate the maximum number of pairs for
OPEN-V, use the formula.
CAUTION: Bitmap areas used for Continuous Access XP Journal are also used for Continuous
Access XP. If you use Continuous Access XP and Continuous Access XP Journal, use the total
number of both pairs.
Journal groups
Continuous Access XP Journal journal groups have the following requirements:
• Each Continuous Access XP Journal pair must be assigned to one and only one journal group.