Installation guide

Introduction to Mirroring Data
HP-UX version 11.00.03 Mirroring Data 4-3
Sample Mirror Configuration
Figure 4-1 shows a possible mirror configuration for six disks, three on each logical
SCSI bus (that is, “A” disks and “B” disks on separate logical SCSI buses), divided
into two physical volume groups.
Figure 4-1. Example of Data Mirroring
In this example, one logical volume uses double mirroring, which means that the
logical volume is mirrored twice, resulting in three copies of the logical volume.
Because this example does not have three physical volume groups, you cannot use
PVG-strict allocation with double mirroring. To accomplish double mirroring with
two physical volume groups, use strict allocation and allocate the mirrors to
different disks.
Recommended Volume Structure
For best data integrity, Stratus recommends that a volume group holding mirrored
logical volumes have the following characteristics:
■ The volume group should be composed of disks attached to two or more
dual-initiated logical SCSI buses.
■ Each physical volume group should be composed of disks controlled by one
logical SCSI bus.
Volume Group
Physical Volume Groups
Double mirror
Contiguous
Noncontagious
No mirror
Logical Volume
Characteristics
3B
3A
2B
2A
1B
1A