HP Cisco MDS 9120 Cisco MDS 9000 Family CLI Configuration Guide - Release 4.x - Page 264

Switchover Mechanisms Chapter 10 Configuring High Availability Send documentation comments to [email protected] 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. Note 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. Switchover Mechanisms Switchovers occur by one of the following two mechanisms: • 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. Once a switchover process has started another switchover process cannot be started on the same switch until a stable standby supervisor module is available. Caution If the standby supervisor module is not in a stable state (ha-standby), a switchover is not performed. HA Switchover Characteristics An HA switchover has the following characteristics: • 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. 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 HA-standby state for the standby supervisor module, then the switchover is possible. 10-2 Cisco MDS 9000 Family CLI Configuration Guide OL-18084-01, Cisco MDS NX-OS Release 4.x