HP StorageWorks XP24000 Continuous Access Journal Software User and Reference Guide, v01 (T5278-96001, June 2007)

Table 13 RAID Level Configuration of Continuous Access Journals
Item
Support Specifications
RAID configuration of the data volume and journal
RAID1, RAID5, and RAID6 can coexist.
volume
RAID1, RAID5, andRAID6 canbecoexisted in thesamejournal group.
Maximum Number
of Pairs
Note: The number of pairs that can be created in a storage system is limited.
Use the numb er of cylinders and bitmap areas to calculate the maximum num b er of pairs that can be
cr eated in a storage system.
• The number of c
ylinders:
The number of pairs of a primary data volume and a secondary data volume are limited. The
number of pa irs depends on the volume capacity (that is, the number of cylinders in the volumes
that form pair
s). If VLL is used, the number of pairs depends on the number of cylinders specified
by VLL. A limit on the number of pairs is applied to both the primary storage system and the
secondary storage system. Use the following formula to calculate the number of cylinders for
different emulation types:
•For OPEN-V:
The number o
fcylinders = (↑ ((↑ (Ma x. LBA/512) ↑)/15) ↑)+1
•The ↑…↑ symbolsaroundavalueindicatethat the valueshouldberounded up to the
nearest integer.
•LBA : L
ogica
lB
lock Address
• Thenumberofrequiredbitmapareas:
The number of bitmap areas to be used by all data volumes that form pairs can be calculated
from the nu
mber of cylinders. This number is called the required number of bitmap areas. Use the
following formula to calculate the required number of bitmap areas for a data volume. The ↑…↑
symbols around a value indicate that the value should be rounded up to the nearest integer.
The required number of bitmap areas = (↑((number of cylinders × 15) ÷ 122,752) ↑)
•number of
cylinders × 15 indicates the number of slots
• 122,752 is the number of slots that a bitmap area can m ana ge
Note: If the required number of bitmap a reas calculated exceeds the total number of bitmap
areas in the storage system, the number of p a irs that can be created will be limited.
Note: If you use LUSE volumes, you must add 1 to the value calculated by the above formula.
• The maxi
mum n um ber of pairs that can be created:
The maximum possible number of pairs that can be created is defined by the number of bitmap
areas in the storage system and the number of bitmap areas required to create pairs.
The number of bitmap areas in the storage system is defined by the capacity of sha red m emory.
The relationship between the capa city of shared memor y and the number of bitmap areas in the
storag
e
system is descr ibed in Table 14 on page 45.
44
Preparing for Continuous Access Journal Operations