Volume Pairs (P-Vols And S-Vols); Continuous Access Xp Asynchronous Consistency Groups; Continuous Access Xp Supported Raid Level Configurations - HP xp12000 User Manual

NOTE: When serial interface connections are used for remote copy operations, controller emulation of
the connected ports of the MCU and RCU can be different. However, when the MCU and RCU are
connected to the same host, controller emulation of the host-connected ports of the MCU and RCU must be
the same.

Volume pairs (P-VOLs and S-VOLs)

Continuous Access XP performs remote copy operations for logical volume pairs you create. Each
Continuous Access XP pair consists of one primary volume (P-VOL) and one secondary volume (S-VOL),
which can be in the same disk array (synchronous only) or different disk arrays. The Continuous Access XP
P-VOLs are primary volumes (LUs) containing original data, and the Continuous Access XP S-VOLs are
secondary or mirrored volumes (LUs) containing replicated or duplicate data. Volumes are copied on an
Open volume basis, and logical volumes should have the same format and capacity (SCSI path definition
is required). During normal Continuous Access XP operations, the P-VOL remains available to all hosts at
all times for read and write I/O operations. During normal Continuous Access XP operations, the RCU
rejects all host-requested write I/Os for the S-VOLs. The S-VOL write enable option allows write access to
an S-VOL while the pair is split, and uses the S-VOL and P-VOL cylinder maps to resynchronize the pair (see
"S-VOL write option" on page 20).
Continuous Access XP supports basic logical unit (LU) types available on the XP12000/XP10000.
Continuous Access XP also supports Volume Manager, CVS, and Cache LUN XP features, ensuring that all
user data can be backed up or duplicated. See
about LU requirements and support.
Continuous Access XP supports a maximum of 8,192 Continuous Access XP pairs (entire RCU). When
Continuous Access XP pairs include size-expanded LUs, the maximum number of pairs decreases. When
the RAID Manager command device is defined, the maximum number of Continuous Access XP pairs in
the XP12000/XP10000 is 8,191.
Continuous Access XP supports the following RAID level configurations.
Table 4

Continuous Access XP supported RAID level configurations

For P-VOL
RAID 1
RAID 1
RAID 5
RAID 1
RAID 5
RAID 5
RAID 6
RAID 6
RAID 6

Continuous Access XP Asynchronous consistency groups

A Continuous Access XP Asynchronous consistency group is a user-defined set of volume pairs across
which update sequence consistency is maintained and ensured at the remote site. Each Continuous Access
XP Async volume pair must be assigned to a consistency group. Continuous Access XP can configure up to
128 consistency groups (0-7F) for each MCU and provides group-based operations for consistency groups
(for example, split and resync group). Use consistency groups to maintain update sequence consistency for
databases spanning multiple volumes, allowing immediate database recovery at the remote site when
needed. See "Continuous Access XP Asynchronous consistency group
information.
16 Continuous Access XP for the XP12000/XP10000
"Logical unit (LU)
For S-VOL
RAID 1
RAID 6
RAID 5
RAID 5
RAID 1
RAID 6
RAID 1
RAID 5
RAID 6
types" on page 31 for further information
operations" on page 23 for further