HP StorageWorks Continuous Access XP user guide for the XP10000/XP12000 (December 2005)

Continuous Access XP user guide for the XP10000/XP12000 41
Use Continuous Access XP and BC in the same disk array and on the same volumes to provide multiple
copies of data at primary and remote sites. Table 10 describes host pair status reporting for Continuous
Access XP volumes, BC XP volumes, and Continuous Access XP/BC shared volumes. Table 11 shows
currency of data on a shared Continuous Access XP/BC volume based on Continuous Access XP and BC
pair status.
For more information abut Business Copy XP, see the HP StorageWorks Business Copy XP User Guide for
the XP10000/XP12000.
NOTE: HP recommends Business Copy (BC) intra-disk array copy operations. If BC is not installed, you
can use Continuous Access XP to copy within the same local disk array. This configuration requires at least
one fibre cable loop.
For shared Continuous Access XP/BC volumes, the Continuous Access XP pair status is reported to the
host if you query the Continuous Access XP P-VOL or S-VOL. To obtain the BC pair status, query the
P-VOL of the BC pair.
BC supports multiple S-VOLs for each P-VOL. If you issue a pair status query to a BC P-VOL (for
example, pairdisplay), the status for only one BC pair is reported (pair with the S-VOL with lowest LDEV
ID). To obtain the pair status for BC pairs with other S-VOLs, direct the host query to the specific S-VOL
using the S-VOL’s LDEV ID in the host command. The BC remote console software displays the LDEV ID
and BC pair status of all S-VOLs associated with a P-VOL.
Figure 15 through Figure 18 show various Continuous Access XP/BC configurations that share volumes.
Continuous Access XP supports synchronous and asynchronous operations for shared Continuous Access
XP/BC volumes.
Table 10 Host pair status reporting for Continuous Access XP, BC, and Continuous Access XP/BC shared
volumes
Number of Continuous
Access XP pairs
Number of BC S-VOLs Pair status reported by disk array
00Simplex
01BC pair status
0 2 or more BC pair status for pair whose S-VOL has lowest LDEV ID
1 0 Continuous Access XP pair status
1 1 Continuous Access XP pair status
1 2 or more Continuous Access XP pair status
Table 11 Data currency of a shared Continuous Access XP/BC volume
Continuous
Access XP pair
status
BC pair status
COPY (PD) PAIR COPY (SP) PSUS COPY (RS/RS-R) PSUE
COPY Not current Not current Not current CURRENT Not current Not current
PAIR Not current Not current Not current CURRENT Not current Not current
PSUS/PSUE Not current CURRENT CURRENT CURRENT CURRENT Not current