HP XP Continuous Access Software - Manual (Page 50)

Table 12 Journal volume specifications
Item Support specifications
Emulation type Same
NOTE:
Only OPEN-V can be used for journal volumes.
Volume capacity Same or different amount of capacity is available
Table 13 list the RAID-level combination of data and journal volumes in the journal group that can be
used for Continuous Access XP Journal.
Table 13 RAID-level configuration of Continuous Access XP Journal
Item Support specifications
RAID configuration of data and journal volumes RAID–1, RAID-5 and RAID-6 can coexist
RAID-1, RAID-5 and RAID-6 can coexist in the same journal group.
Maximum number of pairs
NOTE:
The number of pairs you can create in an array is limited.
Use the number of cylinders and bitmap areas to calculate the maximum number of pairs you can
create in an array.
• Number of cylinders:
The number of pairs of a primary and a secondary data volume is limited. The number of pairs
depends on the volume capacity (that is, the number of cylinders in the volumes forming pairs). If you
use Custom Volume Size (CVS), the number of pairs depends on the number of cylinders that CVS
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.
50 Continuous Access XP Journal operations requirements and restrictions