C H A P T E R 9 Configuring High Availability; Switchover Mechanisms; Ha Switchover Characteristics; Initiating A Switchover - HP Cisco MDS 9020 - Fabric Switch Configuration Manual

Switchover Mechanisms

S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
Note
Switchover Mechanisms
Switchovers occur by one of the following two mechanisms:
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Once a switchover process has started another switchover process cannot be started on the same switch
until a stable standby supervisor module is available.
If the standby supervisor module is not in a stable state (ha-standby), a switchover is not performed.
Caution

HA Switchover Characteristics

An HA switchover has the following characteristics:
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•
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Initiating a Switchover

To manually initiate a switchover from an active supervisor module to a standby supervisor module,
issue the system switchover command. Once issued, another switchover process cannot be started on
the same switch until a stable standby supervisor module is available.
To ensure that an HA switchover is possible, issue the show system redundancy status command or the
show module command. If the command output displays the
module, then the switchover is possible.
Cisco MDS 9000 Family CLI Configuration Guide
9-2
Directors in the Cisco MDS 9500 Series have two supervisor modules (sup-1 and sup-2) in slots 5
and 6 (Cisco MDS 9509 and 9506 Switches) or slots 7 and 8 (Cisco MDS 9513 Switch). When the
switch powers up and both supervisor modules are present, the supervisor module that comes up first
enters the active mode and the supervisor module that comes up second enters the standby mode. If
both supervisor modules come up at the same time, sup-1 becomes active. The standby supervisor
module constantly monitors the active supervisor module. If the active supervisor module fails, the
standby supervisor module takes over without any impact to user traffic.
For high availability, you need to connect the ethernet port for both active and standby
supervisors to the same network or virtual LAN. The active supervisor owns the one IP address
used by these ethernet connections. On a switchover, the newly activated supervisor takes over
this IP address.
The active supervisor module fails and the standby supervisor module automatically takes over.
You manually initiate a switchover from an active supervisor module to a standby supervisor
module.
It is stateful (nondisruptive) because control traffic is not impacted.
It does not disrupt data traffic because the switching modules are not impacted.
Switching modules are not reset.
Chapter 9 Configuring High Availability
state for the standby supervisor
HA-standby
OL-16184-01, Cisco MDS SAN-OS Release 3.x