Compaq External RAID Controller & Subsystem Infortrend - Table 10 - 1 ID Mapping Status (Normal Operation); Table 10 - 2 ID Mapping Status (Controller Failed)

Infortrend10-10
Table 10 - 1 ID Mapping Status (Normal Operation)
Channel ID Status Target Chip
0
(Primary ID)
Active Pri. Controller
channel 0
0
1
(Secondary ID)
Standby Sec. Controller
channel 0
1
(Secondary ID)
Active Sec. Controller
channel 1
1
0
(Primary ID)
Standby Pri. Controller
channel 1
In the event of controller failure (say, the Primary controller fails), the
once inactive ID (chip) will become active:
Table 10 - 2 ID Mapping Status (Controller Failed)
Channel ID Status Target Chip
0
(Primary ID)
Active
Pri. Controller
channel 0
– Failed!
0
1
(Secondary ID)
Standby- becomes
Active!
Sec. Controller
channel 0
1
(Secondary ID)
Active Sec. Controller
channel 1
1
0
(Primary ID)
Standby
Pri. Controller
channel 1-
Failed!
Figure 10 - 8 Controller Failover
For every channel that is actively serving I/Os, there is another on the
alternate controller that stays idle and will inherit the task should its
counterpart fail.
An exception to this is that active IDs may co-exist on single or
multiple host channels. As long as I/O bandwidth is not of the
concern, then standby chips may not be necessary.