Texas Memory Systems RamSan-325/325c - Manual (Page 90)

RamSan-325/325c User’s Manual - 86 -
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)
The “Secondary (Passive, Primary is X)” state 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)
The “Primary (Passive, Secondary is X)” 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)
The “Secondary (Active, Primary is X)” state identifies 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.