Texas Memory Systems 325 - Manual (Page 91)

Primary (Active, Secondary is X)
This state is identical to “Primary (Active)” state with one important
difference: the administrator has selected a secondary controller,
Controller X, to backup this primary controller. If this primary controller
loses its link for an extended period or cannot transmit data for any
reason, the secondary controller mimics the failed controller, preventing
performance loss.
To get a controller into this state: First, configure the primary controller as
“Primary (Active).” Then, from the secondary controller’s setup menu, set
the secondary controller’s high availability to “Secondary (Passive,
Primary is X)” state and choose the primary controller as the primary.
Note: Once the administrator sets a controller as a primary controller with
a backup, it must remain primary until the administrator changes the
secondary controller’s configuration from secondary to primary.
Secondary (Passive, Primary is X)
This state is the sets the controller as secondary to a primary controller,
as mentioned in the section above. To set a controller in this state, first
configure its high availability to “Secondary (Passive, Primary is X)” state
from the “Primary (Active)” state. The controller remains in this state
until the administrator configures it back to “Primary (Active)” state or
until a failover occurs. If a failover occurs, the system copies all of the
attributes of the primary controller to the secondary controller and
activates its links. From this state, all of the secondary controller’s
attributes are meaningless and are not updateable until the administrator
sets the controller back to “Primary (Active)” state.
Primary (Passive, Secondary is X)
This state indicates that the primary controller has experienced a failure;
however, often these failures are not fatal and are recoverable. For
example, if a cable is pulled for an extended period, the link “fails,” but
once the controller is plugged back in, the link becomes usable again.
Since the system copies all attributes of a failed primary controller to the
secondary, the system cannot allow the failed primary controller to come
back online. Instead, the system disables the links, and the original
primary controller becomes a backup for the active secondary controller.
The administrator cannot set this controller back to an active state
directly. To re-activate this controller, either the secondary controller
must fail, or the administrator must re-configure the secondary controller
to “Primary (Active)” state.
Secondary (Active, Primary is X)
This state indicates a secondary controller that has taken over for a failed
primary controller. The administrator originally configured this controller
to backup the primary controller; however, when the primary controller
failed, this controller became an active copy of the primary. In this state,
the primary controller backs up this secondary controller. Changing this
secondary controller to “Primary (Active)” state resets this controller and
the primary controller. In addition, resetting the controller causes the
system to temporarily loose the link. Reads and writes occurring when
RamSan-300/320/325 User’s Manual - 87 -