HP XP P9000 Continuous Access Synchronous for Mainframe Systems User Guide

DASD fast write requirements
DASD fast write (DFW) is required at the main and remote system only when Required is specified
for the PPRC DFW to S-VOL option. If DFW to an S-VOL is blocked, but the pair was established
with the Required option specified, the main system detects DFW OFF at the S-VOL and suspends
the pair. The default for Cnt Ac-S Z pairs created using PPRC commands is Not Required, therefore
they are not suspended when DFW to S-VOL is blocked.
The DFW to S-VOL setting does not affect P-VOL I/O performance. If one side of cache is closed
due to a remote system failure, the copy operation still uses DFW. The difference between not
required and required is that new pairs cannot be established with the required option when one
side of RCU cache is closed. In this case, the Add Pair operation fails (This restriction applies only
when the CU emulation type of RCU is 3390).
Requirements for XP P9500 with earlier model storage systems
You can pair volumes on the XP P9500 with volumes on XP24000/XP20000 Disk Array and
XP12000 Disk Array/XP10000 Disk Array, unless you create a consistency group using multiple
storage systems. In that case, pair volumes on an XP P9500 cannot be paired with volumes on
XP24000/XP20000 Disk Array and XP12000 Disk Array/XP10000 Disk Array.
• The following table shows the number of CUs and the CU range for each storage system:
CU range# of CUsDisk array
0x00 to 0xfe255XP P9500
0x00 to 0xfe255XP24000/XP20000 Disk Array
0x00 to 0x3f64XP12000 Disk Array/XP10000 Disk Array
• When you connect the XP P9500 with XP24000/XP20000 Disk Array, the ranges for ports,
LUNs and CUs that can be specified are unrestricted, because both storage systems have the
same number for these resources.
• When you connect the XP P9500 with XP12000 Disk Array/XP10000 Disk Array, the ranges
for port numbers, LUNs and CUs are restricted. Both storage systems are limited to the following
ranges:
CU:LDEV *LUNPort numbers
0x00:00 to 0x3F:FF0x0000 to 0x03FF1A to GR
*
The LDKC number, 00, is also used in the CU # for XP P9500 and XP24000/XP20000 Disk Array.
• Any model can be the MCU or RCU.
• When connecting XP P9500 with XP12000 Disk Array/XP10000 Disk Array or
XP24000/XP20000 Disk Array, contact your HP representative for information regarding the
supported microcode versions.
• If you are creating a pair using the previous model storage system at the remote site, make
sure that the main and remote system each have a unique 5-digit serial number.
S-VOL Read and other system options
You can tailor XP P9500 storage systems to enable the S-VOL Read option and other functions.
System option modes related to Cnt Ac-S Z and PPRC operations are shown in the following table.
(For more information about I/O to the S-VOL, see “Preparations for allowing I/O to the S-VOL”
(page 35).)
Storage system preparation 29