HP XP P9000 Continuous Access Synchronous for Mainframe Systems User Guide

• “Preparations for allowing I/O to the S-VOL” (page 35)
• “Fence Level options for I/O to the P-VOL after suspension” (page 36)
• “Differential data options” (page 36)
• “Maximum number of pairs supported” (page 37)
• Options and settings for number of pairs copied, and their priority, during the initial copy
and resync operations. See “Priority for initial copy operations and scheduling order” (page 38)
Pair volume requirements and recommendations
The following is provided to help you prepare Cnt Ac-S Z volumes:
• A volume can be assigned to only one pair.
• The S-VOL must be equal-to or larger-than the P-VOL. However, if the S-VOL is larger than the
P-VOL, the swap operation cannot be performed.
• Cnt Ac-S Z requires a one-to-one relationship between the P-VOL and S-VOL. The P-VOL cannot
be copied to more than one S-VOL, and an S-VOL cannot have more than one P-VOL.
• Logical Volume Images (LVIs)
All basic mainframe LVIs that can be configured on the XPP9500 system are supported
for Cnt Ac-S Z; for example, 3390 3, 3R, 9, L.
◦
◦ Multi-platform volumes (3390 3A/B/C) are not supported.
◦ Data can be copied between volumes with the same emulation and capacity (for example,
3390 3R to 3390 3R).
◦ Data can be copied from smaller volumes to larger volumes (for example, 3390 3 to
3390 9) of the same emulation (VTOC expansion must be used).
However, HP strongly recommends that you limit copying from a smaller volume to a
larger volume to data migration purposes and not disaster recovery. Under the disaster
recovery scenario, you would not be able to perform Cnt Ac-S Z operations in the reverse
direction, from the remote system to the main system, because a larger volume cannot
be copied to a smaller volume.
Also, with larger-to-smaller volumes, if the BCM SUSPEND command is issued, you cannot
use the remote system R/W option and Reverse option.
• Pair volumes have the following disk track format requirements. Cnt Ac-S Z cannot detect
exceptions to these requirements. The main system will abort the initial copy operation if the
track format for both the P-VOL and S-VOL does not meet the following requirements:
◦ The P-VOL and S-VOL must have the same track format.
◦ Record zero (R0) must be standard format, with key length of zero and data length of
eight. The main system will abort the initial copy operation if R0 is not standard format.
◦ The CCHH (logical cylinder address and logical head address) of R0 must be identical
to the physical cylinder address and physical head address of the track.
◦ The CCHH of each user record in a track must be unique.
• Cnt Ac-S Z operates on volumes rather than on datasets; multi-volume datasets require special
attention. For complete duplication and recovery of a multi-volume dataset (for example, a
large database file that spans several volumes), make sure that all volumes of the file are
copied to Cnt Ac-S Z S-VOL.
• Cnt Ac-S Z pair volumes can be shared with non-Cnt Ac-S Z HP software products. See “Sharing
Continuous Access Synchronous Z volumes” (page 50) for more information.
34 Planning for Continuous Access Synchronous Z