Compaq Infortrend manual Limitations, Configurable Parameters, Primary or Secondary

10.2.2 Limitations

• Both controllers must be exactly the same. Namely, they must operate with the same firmware version, the same size of memory, the same number of host and drive channels, etc. If battery backup is preferred, both should be installed with a battery module.

• The takeover process should take less than one second (using SCSI or Fibre for controller communications) to complete.

• In redundant mode, each controller takes an ID on each channel bus. This leaves the maximum number for disk drives on a SCSI bus to be 14.

• Connection through Fibre hubs or switches is necessary for joining host (Fibre) interfaces between controllers. The EonRAID 2510FR is an exception. Its type-1 ports come with an onboard hub.

• The controller defaults for ID settings are listed below:

Host	Host channel	Drive channel
interface	(Primary/Secondary)	(Primary/Secondary)
SCSI	0 / 1…	7 / 6
Fibre	112 / 113…	119 / 120

• SCSI IDs 8 (PID) and 9 (SID) are the recommended defaults to the drive channels of the SCSI-based dual-controller chassis using an integrated backplane.

10.2.3 Configurable Parameters

Primary or Secondary

If necessary, users can specify a particular controller as Primary or Secondary. By setting each controller to the "Autocfg" mode, the controllers will decide between themselves which is the Primary and which is the Secondary.

The controller firmware recognizes the two controllers used in a redundant configuration as Primary or Secondary. Two controllers behave as one Primary controller.

Once the redundant configuration takes effect, user's configurations and settings can only be done on the Primary controller. The Secondary controller then synchronizes with the configuration of the Primary controller, making the configurations of two controllers exactly the same.

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