Compaq External RAID Controller & Subsystem Bedienungsanleitung PDF herunterladen (Seite 225)

Redundant Controller

10-12

D.Traffic Distribution and Failover Process

The diagram below illustrates a four-channel configuration using

channel 0 as the communications path. Channel 1 serves as the host

interface and multiple IDs are created to facilitate active-active

operation. Each controller occupies either a Primary ID or a

Secondary ID on drive channels. One logical unit is assigned to the

Primary controller and the other the Secondary controller. In the

event when one controller fails, the existing controller will inherit IDs

from the failed controller and continue I/Os.

Figure 10 - 9 Traffic Distribution

Logical Drive 0 Logical Drive 1

Host LUN Mapping ID0 / LUN

* (PID)

ID1 / LUN

* (SID)

Logical Drive Assignment Primary Secondary

Drive Channel 2 3

When creating a logical unit, users will be prompted to assign the

logical unit either to the Primary or to the Secondary controller. Once

the assignment is done, logical unit(s) assigned to the Primary

controller can only be mapped to the Primary IDs on host channel;

Logical unit(s) assigned to the Secondary controller can only be

mapped to the Secondary IDs on host channel.

The channel ID (Primary/Secondary) assignment for a SCSI controller

should look like this:

Primary Controller ID Secondary Controller ID

Host Chl SCSI ID PID = 0 SID = 1

Drive Chl SCSI ID 7 (or 8 for the dual

redundant chassis)

6 suggested (or 9 for the

dual redundant chassis)

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Compaq External RAID Controller & Subsystem Bedienungsanleitung Seite 225