User`s guide

In these cases, the command is directed to the correct controller:
• THIS_CONTROLLER refers to the controller to which the terminal is
connected or which is the target of the virtual terminal connection.
• OTHER_CONTROLLER refers to the other controller in the dual-redundant
pair.
Note
Devices, stripesets, RAIDsets, and mirrorsets are defined as containers.
All changes in container configuration are automatically communicated
between the two controllers.
2.3.1 Setting Failover
To place both controllers into a failover configuration, enter the following
command:
CLI> SET FAILOVER COPY= configuration-source
Where configuration-source is either THIS_CONTROLLER or
OTHER_CONTROLLER, depending on where the ‘‘good’’ copy of configuration
information is located.
CAUTION
Whenever you add a new controller to an existing controller to form a
dual-redundant pair, enter initial parameters such as MAX_NODES,
controller ID or SCSI target IDs, SCS node names and allocation classes,
(as appropriate for your controller model), before entering the SET
FAILOVER command. This eliminates problems in case your new
controller module’s ID is set to the same ID as another member in the
cluster.
DIGITAL recommends that the controllers be set for failover before any
device configuration commands are entered (for example, ADD DISK,
ADD UNIT, or ADD RAIDset). Then, as devices, storagesets, and units
are added to one controller’s configuration, they are automatically added
to the other controller’s configuration.
IMPORTANT: Given two unconfigured controllers, it is possible to fully
configure one controller, then enter the SET FAILOVER command.
However, if the ‘‘wrong’’ controller is specified after the COPY= qualifier,
all device configuration information will be lost. Never blindly specify SET
FAILOVER. Always know where your ‘‘good’’ configuration information is
located.
Due to the amount of information that must be passed between the two
controllers, the SET FAILOVER command may take up to 1 minute to complete.
When setting dual-redundant controllers for failover, make sure the target
controller (the controller you are copying the configuration to) has no cache errors
or unwritten cache data. Delete any remaining, configured units on the target
controller to verify there are no cache errors before entering the SET FAILOVER
command. Deleting units from the target controller will not create problems
Controller Technical Description 2–17