HP StorageWorks XP Business Copy User Guide: HP XP12000 Disk Array HP XP10000 Disk Array HP 200 Storage Virtualization System (T1713-96028, June 2010)

• The root volume is the P-VOL of the L1 pair, which is the original BC pair. You can add up to three
S-VOLs (node volumes) to a root volume.
• The node volume is the S-VOL (reserved) of an L1 pair and the P-VOL of an L2 pair. You can add
up to two S-VOLs (leaf volumes) to a node volume.
• The leaf volume is the S-VOL (reserved) of an L2 cascade pair.
Table 8 shows the relationship between L1 pair status and availability of BC pair operations on the
associated L2 pairs. To split an L2 pair, you must first split the L1 pair (L1 status = PSUS). The reverse
and quick restore pairresync operations cannot be used for L2 pairs. Table 9 shows the relationship
between L2 pair status and availability of pair operations on the associated L1 pairs. (CMD RJT =
command rejected.) If you delete an L1 pair containing an L2 pair, the L2 pair becomes the L1 pair.
NOTE:
• Combining L1 and L2 pairs with Continuous Access XP volumes is allowed; however, Continuous
Access XP considers node and leaf volumes as secondary volumes (S-VOLs).
• When a P-VOL is paired with more than one S-VOL, the disk array assumes there are the same
number of virtual P-VOLs. For example, when a P-VOL is paired with three S-VOLs, there is only
one real P-VOL, but the disk array assumes there are three virtual P-VOLs. A Virtual P-VOL is
called an MU (Mirror Unit).
• “MU#” in Figure 12 means MU number, which identifies each MU. MU#=1 under S-VOL1 means
the MU number of the P-VOL that is paired with the S-VOL1 is 1.
Table 8 Relationship between L1 pair status and L2 pair operations
L2 Pair OperationsL1 Pair
Status
Pairsplit-
S
Pairsplit-
E
Reverse/ Quick Re-
store
Pairre-
sync
PairsplitPaircre-
ate
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKCOPY(PD)
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKPAIR
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKCOPY(SP)
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKPSUS(SP)
OKOK
NO
(CMD RJT)
OKOKOKPSUS
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKCOPY(RS)
OKOK
NO
(CMD RJT)
OK
NO
(CMD RJT)
OKCOPY(RS-R)
Business Copy XP (BC) for the Array34