High Availability on StacksStacks have master and standby management units analogous to Dell Networking route processor modules (RPM).The master unit synchronizes the running configuration and protocol states so that the system fails over in the event of a hardwareor software fault on the master unit. In such an event, or when the master unit is removed, the standby unit becomes the stackmanager and Dell Networking OS elects a new standby unit. Dell Networking OS resets the failed master unit: after online, itbecomes a member unit; the remaining members remain online.Example of Stack Manager RedundancyDell#show redundancy-- Stack-unit Status --------------------------------------------------Mgmt ID: 0Stack-unit ID: 5Stack-unit Redundancy Role: PrimaryStack-unit State: ActiveStack-unit SW Version: 1-0(0-3387)Link to Peer: Up-- PEER Stack-unit Status --------------------------------------------------Stack-unit State: StandbyPeer Stack-unit ID: 2Stack-unit SW Version: 1-0(0-3387)-- Stack-unit Redundancy Configuration --------------------------------------------------Primary Stack-unit: mgmt-id 0Auto Data Sync: FullFailover Type: Hot FailoverAuto reboot Stack-unit: DisabledAuto failover limit: 3 times in 60 minutes-- Stack-unit Failover Record --------------------------------------------------Failover Count: 0Last failover timestamp: NoneLast failover Reason: NoneLast failover type: None-- Last Data Block Sync Record: --------------------------------------------------stack-unit Config: succeeded Nov 25 2014 15:29:58Start-up Config: succeeded Nov 25 2014 15:29:58Runtime Event Log: succeeded Nov 25 2014 15:29:58Running Config: succeeded Nov 25 2014 15:29:58ACL Mgr: succeeded Nov 25 2014 15:29:58LACP: no block sync doneSTP: no block sync doneSPAN: no block sync doneManagement Access on StacksYou can access the stack via the console port or VTY line.• Console access — You may access the stack through the console port of the master unit (stack manager) only. Similar to astandby RPM, the console port of the standby unit does not provide management capability; only a limited number of commandsare available. Member units provide a limited set of commands.• Remote access — You may access the master unit and standby unit in a stack through the dedicated management Ethernetinterfaces with SNMP, SSH, or via Telnet.Example of Accessing Non-Master Units on a Stack via the Console Port-----------------CONSOLE ACCESS ON A STANDBY----------------------------Dell(standby)#?Stacking 825
