HP StorageWorks XP Remote Web Console Software - Manual (Page 16)

•
To calculate the maximum number of pairs that you can create:
Where the added shared memory is one pair:
The maximum number of pairs that you can create = (
↓ (11,605 ÷ Number of bitmap
areas)
↓ )
◦
The
↓ symbols around a value indicate that the value should be rounded down to the
former integer.
◦ Where the added shared memory is two pairs:
The maximum number of pairs that you can create = (
↓ (28,671 ÷ Number of bitmap
areas)
↓ )
The
↓ symbols around a value indicate that the value should be rounded down to the
former integer.
NOTE: The maximum number of pairs that you can create cannot exceed 16,384.
Table 3 Maximum pairs per emulation type, excluding custom-sized volumes
Maximum pairs (added
shared memory: 2 pairs) Maximum pairs (added
shared memory: 1 pair) Number of
bitmap areas Number of
cylinders Emulation type
16,384 11,605 1 3,339 OPEN-3
14,335 5,802 2 9,967 OPEN-8
14,335 5,802 2 10,017 2 OPEN-9
9,557 3,868 3 19,760 3 OPEN-E
4,095 1,657 7 49,440 7 OPEN-L
NOTE: The capacity of OPEN-V is variable. To get the maximum number of OPEN-V pairs, use the formula.
CAUTION: The bitmap areas that are used for XP Continuous Access are shared with XP
Continuous Access Journal. If you use both XP Continuous Access and XP Continuous Access
Journal, use the total value of both pairs.
•
The type of difference management (track or cylinder) differs according to the combination
of arrays. The differential data is stored in units of tracks or cylinders (see
Table 4 (page 16) ).
Table 4 Unit for storing the differential data
XP1024/XP128 XP12000/XP10000/SVS200
Track or Cylinder Track or Cylinder XP12000/XP10000 and SVS 200
Track or Cylinder Track or Cylinder XP1024/XP128
CAUTION: You may specify the type of difference management when you create a pair
with the Paircreate pane (see “Creating XP Continuous Access volume pairs (Paircreate)”
(page 99) ). If an XP12000 disk array is connected with an XP1024/XP128 disk array, type
of difference management is applied as it is when you specify the unit. If an XP12000 array
is connected with an XP1024/XP128 array, the differential data is stored in units of cylinders.
If an XP12000 array is connected with an XP1024/XP128 or XP1024/XP128 array, the
maximum number of pairs that you can create is the lesser number by comparing both numbers.
If an XP12000 disk array is connected with an XP1024/XP128 disk array, you can use XP
Remote Web Console or XP RAID Manager software to specify the type of difference
16 Overview of XP Continuous Access operations