Chapter 4: Drive Connection 65
Drive Channel
Redundancy for
the CE4900
Controller-Drive
Tray
Each controller has one drive channel, and each drive channel has two ports.
Therefore, each controller has two drive ports. A controller-drive tray has two
redundant path pairs that are formed using one drive channel of controller A and one
drive channel of controller B. The following figure shows the redundant pairs in a
controller-drive tray. The following table lists the numbers of the redundant path pairs
and the drive ports of the drive channels from which the redundant path pairs are
formed.
NOTE To maintain data access in the event of the failure of a controller, an ESM, or
a drive channel, you must connect a drive tray or a string of drive trays to both drive
channels on a redundant path pair.
Figure 5 Redundant Path Pairs on the CE4900 Controller-Drive Tray
Table 3 Redundant Path Pairs on the CE4900 Controller-Drive Tray
Redundant
Path Pairs
Drive Ports on
Controller A
Drive Channels
on Controller A
Ports on
Controller B
Drive Channels
on Controller B
1 Port 2 Channel 1 Port 1 Channel 2
2 Port 1 Channel 1 Port 2 Channel 2