HP XP Racks - Manual (Page 19)

Planning pairs and pair volumes
This section discusses requirements, options, and settings you need for setting up pairs and pair
volumes. You begin by:
•
Identifying data and volumes at the local site that you want to protect with a backup
•
Setting up volumes at the remote site that will hold copied data.
The following helps ensure that the pairs you create fit your requirements.
•
“Pair volume requirements and recommendations” (page 19)
•
“About allowing I/O to the S-VOL” (page 20)
•
“Allowing I/O to the P-VOL after a split—Fence Level options” (page 20)
•
“Differential data ” (page 21)
•
“Maximum number of pairs supported” (page 21)
•
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 23)
Pair volume requirements and recommendations
The following is provided to help you prepare Continuous Access Synchronous volumes:
•
A volume can be assigned to only one pair.
•
Logical units on the primary and secondary storage systems must be defined and formatted
prior to pairing.
•
The P-VOL and S-VOL must be equal in size.
•
Continuous Access Synchronous 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 Unit (LU) Types
Continuous Access Synchronous supports the basic LU types that can be configured on
the XP7 (for example, OPEN 3, OPEN E, OPEN 8, OPEN 9, OPEN L, OPEN V). ◦
◦ Pair volumes must consist of LUs of the same type and capacity (for example, OPEN 3
to OPEN 3). The P-VOL and S-VOL LU types display in Remote Web Console.
◦ Multi-platform volumes (for example, 3390 3A/B/C) cannot be assigned to pairs. Contact
your HP account team for the latest information about supported devices for your platform.
•
Continuous Access Synchronous operates on volumes rather than on files; multi-volume files
require special attention. For complete duplication and recovery of a multi-volume file (for
example, a large database file that spans several volumes), make sure that all volumes of the
file are copied to Continuous Access Synchronous S-VOL.
•
Continuous Access Synchronous pair volumes can be shared with non-Continuous Access
Synchronous HP software products. See
“Sharing Continuous Access Synchronous volumes”
(page 37) for more information.
•
Continuous Access Synchronous supports Virtual LVI/LUN. This allows you to configure LUs
that are smaller than standard LUs. When custom-size LUs are assigned to a Continuous Access
Synchronous 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.
Planning pairs and pair volumes 19