HP XP7 Storage - Manual (Page 53)

Provisioning Z automatically releases pages with reclaiming zero pages in the THP V-VOL,
thus increasing usable capacity.
Pages that include control cylinder information are not released (see next).
◦ If a pair does not include a THP V-VOL, volume capacity is counted toward Cnt Ac-S Z
license capacity.
If a pair includes a THP V-VOL, only the allocated page capacity of volume capacity is
counted toward Cnt Ac-S Z license capacity.
If a THP V-VOL and a non-THP V-VOL are included in a pair, the page capacity and/or
license capacity counted in the P-VOL and the S-VOL may be different. This applies even
when both P-VOL and S-VOL include THP V-VOLs, because the page capacity of the P-VOL
or the S-VOL changes by a relocated pool or released page or other action.
◦ Page or license capacity can also differ between the P-VOL and S-VOL for the following
reasons:
- The Cnt Ac-S Z copy process overwrites S-VOL track data, even when the track is assigned
to pages with no records in the P-VOL. This happens because when S-VOL track data is
overwritten, Cnt Ac-S Z updates the control cylinder information, which manages track
information. Additional pages may result for holding control cylinder information in the
S-VOL, and these pages cannot released. Thus, the number of pages in the S-VOL may
be greater than in the P-VOL.
- When you update the S-VOL in Suspended status, a page that includes control cylinder
information may be assigned. Pages that include the control cylinder information are not
released, thus, the number of pages in the S-VOL may be greater than P-VOL.
- When the Cnt Ac-S Z copy process is run for zero data pages in the P-VOL, the S-VOL
may not assign zero data pages, thus there can be fewer pages in the S-VOL.
◦ Cnt Ac-S Z license capacity can be less than THP V-VOL page capacity, however it cannot
exceed page capacity.
•
If the volume you will use for a Cnt Ac-S Z S-VOL is a THP V-VOL and its capacity is more than
the P-VOL’s capacity, before creating the pair, delete the S-VOL’s datasets using the z/OS
Security Server RACF (Resource Access Control Facility) function. (See the appropriate IBM
documents for instructions.)
•
When you run data migration from an P-VOL in an earlier storage model to a DP-VOL RVOL,
the DP-VOL S-VOL may consume the same page capacity as the P-VOL.
For more information, see the HP XP7 Provisioning for Mainframe Systems User Guide.
global virtualization
Pairs can be created using volumes in a virtual storage machine. Please note the following:
•
Though Remote Web Console displays the virtual LDEV ID of a volume belonging to a virtual
storage machine, make sure when running pair operations in Remote Web Console that you
specify the physical XP7 LDEV ID.
•
A volume’s virtual ID used with Continuous Access Synchronous cannot be deleted.
global virtualization 53