Redundant Controller
10-7
Drive Channel:
Since all channels are strung between two controllers, each
channel is connected to two chip processors, and each processor
must occupy one channel ID. In redundant mode, both a Primary
and a Secondary ID must be present on drive channels.
!
The Primary-Secondary relationship between the controllers is
automatically determined by firmware.
!
You may have to create Primary and Secondary IDs separately on
the host and drive channels if these IDs are not available. The
configuration procedure will be discussed in section "10.3".
Mapping
!
A logical unit made available through a Primary ID will be
managed by the Primary controller, and that through a Secondary
ID by the Secondary controller.
!
Each channel ID (or an LUN under ID) will act as one virtual
storage volume to the host computer.
Figure 10 - 5 Mapping System Drives (Mapping LUNs)
! The diagram above displays a single host computer with two
HBA cards allowing the connection of dual I/O paths. A host
port ID is presented on each host port as the Primary ID or
Secondary ID. Users may then map any logical configuration of
drives to these LUN numbers. The result is that workload can be
