HP P9000 Continuous Access Synchronous User Guide (AV400-96400, October 2011)

Primary (MCU), secondary (RCU) systems
The primary system manages the P-VOL and the following operations:
• Host I/O operations to the P-VOL
• Initial copy and update copy operations between the P-VOL and S-VOL
• Pair status and configuration information
The secondary system manages the S-VOL and the following operations:
• Remote copy operations issued by the primary system
• Assists in managing pair status and configuration (for example, rejects write I/Os to the S-VOL)
The P9500 CU can function simultaneously as a primary system for one or more P-VOL, and as a
secondary system for one or more S-VOL. This kind of configuration requires that data paths and
Fibre Channel ports to be properly configured for both copy directions.
When you use XP12000 Disk Array/XP10000 Disk Array for MCU or RCU, CU number which
can be used is limited. The following table provides the range of CU number when P9500,
XP24000/XP20000 Disk Array, or XP12000 Disk Array/XP10000 Disk Array is used for MCU
or RCU.
Table 1 CU number range when P9500, XP24000/XP20000 Disk Array, or XP12000 Disk
Array/XP10000 Disk Array is used for MCU or RCU
RCUMCU
P9500XP24000/XP20000 Disk
Array
XP12000 Disk
Array/XP10000 Disk Array
MCU:0x00 to 0x3fMCU:0x00 to 0x3fMCU:0x00 to 0x3fXP12000 Disk
Array/XP10000 Disk Array
RCU:0x00 to 0x3fRCU:0x00 to 0x3fRCU:0x00 to 0x3f
MCU:0x00 to 0xfeMCU:0x00 to 0xfeMCU:0x00 to 0x3fXP24000/XP20000 Disk
Array
RCU:0x00 to 0xfeRCU:0x00 to 0xfeRCU:0x00 to 0x3f
MCU:0x00 to 0xfeMCU:0x00 to 0xfeMCU:0x00 to 0x3fP9500
RCU:0x00 to 0xfeRCU:0x00 to 0xfeRCU:0x00 to 0x3f
CAUTION: If you are creating a Continuous Access Synchronous pair with different series of
storage systems (for example, P9500 and XP12000 Disk Array/XP10000 Disk Array) make sure
that each storage system has a unique serial number. It is possible that a serial number overlap
could occur (although this is extremely rare). If you have two storage systems with the same serial
number and you need to configure remote copy pairs between the two storage systems, contact
your HP account team for assistance.
Volume pairs
As described above, original data is stored in the P-VOL and the remote copy is stored in the
S-VOL. The pair can be split, resynchronized, reverse resynchronized, and returned to the SMPL
state.
• When paired, the volumes are synchronized.
• When split, new data is sent to the P-VOL but not the S-VOL.
• When resynchronized, changed data is copied to the S-VOL.
• When necessary, data in the S-VOL can be copied to the P-VOL.
During normal operations, the P-VOL remains available to the host for read and write I/O operations.
The secondary system rejects write I/Os for the S-VOL, unless the write-enable option is specified
8 Continuous Access Synchronous overview