SCF Reference Manual for the Storage Subsystem (G06.28+, H06.05+, J06.03+)

The primary and backup paths go to the primary device.
A mirrored device, such as a mirrored disk, can be accessed through an additional two paths: a
mirror path and a mirror-backup path. The paths are set by these attributes of the ADD command
when the device is configured:
MBACKUPLOCATIONMIRRORLOCATION
MBACKUPSACMIRRORSAC
The primary and backup paths go to the primary device. The mirror and mirror-backup paths go
the mirror device.
You can make two paths to a mirror volume active at the same time: one path to the primary device
(either -P or -B) and one path to the mirror device (either -M or -MB). To make a path active, use
the SWITCH command. For an example, see “Changing the Active Path for a Disk” (page 112).
Primary Disk
A mirrored disk volume has two disks: a primary disk and a mirror disk. This logical combination
of two disks is set by the PRIMARYLOCATION and MIRRORLOCATION attributes of the ADD
command when the disk is configured.
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