Hitachi HPAV for z/OS for the XP128/XP1024/XP12000/XP10000 (HITA737-96003, March 2007)
HPAV for z/OS user guide for the XP128/XP1024/XP12000/XP10000 15
CAUTION: The following restrictions apply if XRC will be used with HPAV:
• Ensure that the emulation type of all LCUs is 2105 or 2107. Do not intermix 2105 or 2107 emulation with
other emulation types within the same disk array.
• If XRC volumes already exist, complete the following steps to change to 2105 or 2107 emulation:
a. Stop all jobs and delete all XRC pairs.
b. Change the DKC emulation type of all CHA packages in the disk array to 2105 or 2107.
c. Restart jobs and re-establish XRC pairs.
Maximizing Your HPAV Results
To maximize your results from HPAV operations, be aware of the following:
• The best results can be obtained if the number of aliases per CU image is equal to the number of
available channel paths minus one. If the number of aliases is specified this way, I/O operations can
use all channel paths, thus providing the best results.
• HPAV may not produce good results when many channel paths are used. If all channel paths are used,
good HPAV results cannot be expected.
• The unused device addresses in the XP1024/XP128/XP12000/XP10000 are used as alias devices. If
you use most of the unused device addresses for aliases, you will only have a small amount of free
devices available. If you determine that a large number of aliases will be required, consider adding
more disks to ensure that storage will be available when needed.
• HPAV may not provide good results for devices that are always shared and used by multiple host
systems. For access by multiple hosts, use the Multiple Allegiance (MA) host software function
supported by the XP1024/XP128/XP12000/XP10000.
• If dynamic HPAV can be used in all systems, expect good results if you assign eight to sixteen (8-16)
aliases to each CU image.
• The recommended ratio of base devices to alias devices is 1:3. Table 4 shows examples of calculating
the number of base and alias devices for a CU image with 256 devices. If you know the types of jobs
Functions that cannot be used concurrently with HPAV • Hitachi Multiplatform Backup/Restore (HMBR)
• Virtual LUN
• Cache LUN XP
• Business Copy (BC) XP
• Continuous Access (CA) XP
Functions that can be used concurrently with HPAV
NOTE: Note on GDPS: Please refer to the HP
StorageWorks Continuous Access XP user
NOTE: Note on GDPS: Please refer to the HP
StorageWorks Continuous Access XP
userXP12000/XP10000/SVS200 for important
information on GDPS support for 2105 or 2107
emulation.
• Virtual LVI
• Hitachi FlashAccess for S/390
• SANtinel - S/390
• TrueCopy (TC390)
• ShadowImage (SI390)
• Universal Replicator for z/OS
• PPRC
CAUTION: The device used as a journal volume
of Universal Replicator for z/OS® cannot be used
as a base device.
CAUTION:
•
Extended Remote Copy (XRC) with restrictions (see
Caution
below)
Table 3 Requirements and restrictions for HPAV (continued)
Item Requirement and/or Restriction