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•(Β) = 30,718 when additional shared memory for differential tables is installed.
For example, if you create 10 pairs of LUSE volumes consisting of three OPEN-3 volumes, use the
following equation:
(1x3)x10=30≤ 13,6 52
Since 30 is less than 13,652, 10 pairs of LUSE volumes consisting of three OPEN-3 volumes can
be created.
NOTE:
WhentheemulationtypeisOPEN-3,andthecapacityofthevolumeis2,403,360KB,thenumberof
differential tables required for a pair is 1.
BC operations
Set reserve attribute operation
This operation reserves a volume so it can be used as a BC S-VOL. Reserved volumes can only be used as
BC S-VOLs. The disk array rejects all write operations to reserved volumes (unless in split (PSUS) status or
PSUS(SP)).Youcanreserveupto4,095volumesinonediskarray.UsetheSetReserveAttributewindow
(see Setting reserve attributes) to reserve volumes for use as BC S-VOLs.
A volume might be reserved for BC to ensure that a server does not mount it before BC can use it in a
pair. BC cannot use a volume as an S-VOL if it is being used by a server.
NOTE:
BC leaf volumes (L2 cascade pair) also function as S-VOLs and must be reserved prior to being assigned
to an L2 cascade pair.
Reset reserve attribute operation
This operation unreserves a volume so it can be mounted and accessed by all hosts. After you reset the
reserve attribute, the disk array accepts all subsequent I/O operations to the volume. Use the Reset
Reserve Attribute window (see Resetting reserve attributes) to unreserve volumes.
Paircrea
te operation
This operation establishes the new BC pairs. The volume that will be the P-VOL must be in the SMPL
(simplex)state,andthevolumethatwillbetheS-VOLmustbeintheSMPLstatebeforebeingaddedto
a BC pair.
NOTE:
You can reserve the S-VOL before creating a pair, but you can also create a pair with an unreserved
S-VOL. Use the Paircreate window (see Creating BC pairs (Paircreate)) to create new BC volume pairs.
Initial copy operation
This operation occurs when you create a new volume pair (see Figure 2). The BC initial copy operation
copies all data on the P-VOL to the associated S-VOL. The P-VOL remains available to all hosts for read
and write I/Os throughout the initial copy operation. After the initial copy is complete, the update
copy operation duplicates write operations performed on the P-VOL during the initial copy operation at
the S-VOL.
Business Copy XP user guide
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