HP XP7 Storage - Manual (Page 35)

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 primary 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.
•
Continuous Access Synchronous 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 Continuous Access Synchronous Z S-VOL.
•
Continuous Access Synchronous Z pair volumes can be shared with non-Continuous Access
Synchronous Z HP software products. See
“Sharing Continuous Access Synchronous Z volumes”
(page 50) for more information.
•
Continuous Access Synchronous Z supports Virtual LVI. This allows you to configure LVIs that
are smaller than standard LVIs. When custom-size LVIs are assigned to a Continuous Access
Synchronous Z pair, the S-VOL must have the same capacity as the P-VOL. Remote Web
Console displays the size of P-VOLs and S-VOL.
•
Before creating multiple pairs during the Create Pairs operation, make sure to set up S-VOL
LUNs to allow the system to correctly match them to P-VOLs.
You must do this because, even though you select multiple volumes as P-VOLs, you specify
just one S-VOL. The system automatically assigns subsequent secondary system LUs as S-VOLs
based on the option you specify for Selection Type. These are the options:
◦ Interval: The interval you specify will be skipped between LU numbers in the secondary
system.
For example, suppose you specify LDEV 01 as the initial (base) S-VOL, and specify 3 for
Interval. This results in secondary system LU 04 being assigned to the next P-VOL, 07
assigned to the subsequent P-VOL, and so on. To use Interval, you set up secondary system
LU numbers according to the interval between them.
◦ Relative Primary Volume. The difference is calculated between the LDEV numbers of two
successive P-VOLs. S-VOLs are assigned according to the closest LDEV number.
For example, if the LDEV numbers of three P-VOLs are 01, 05, and 06; and you set LDEV
numbers for the initial S-VOL (Base Secondary Volume) at 02, the LDEV numbers of the
three S-VOLs will be set at 02, 06, and 07, respectively.
Precautions for duplicate VOLSERs
When the P-VOL is copied to the S-VOL during the initial copy operation, the P-VOL VOLSER
(Volume Serial Number) is also copied to the S-VOL. Therefore, the P-VOL and S-VOL have the
same VOLSER. Because the host operating system does not allow duplicate VOLSERs, the host
system administrator must take precautions to prevent system problems related to duplicate VOLSERs
(such as defining S-VOLs not to come online automatically).
Planning pairs and pair volumes 35