Information About High Availability
The purpose of High Availability (HA) is to limit the impact of failures—both hardware and software— within a system. The Cisco NX-OS operating system is designed for high availability at the network, system, and service levels.
The following Cisco NX-OS features minimize or prevent traffic disruption in the event of a failure:
-
Redundancy— redundancy at every aspect of the software architecture.
-
Isolation of processes— isolation between software components to prevent a failure within one process disrupting other processes.
-
Restartability—Most system functions and services are isolated so that they can be restarted independently after a failure while other services continue to run. In addition, most system services can perform stateful restarts, which allow the service to resume operations transparently to other services.
-
Supervisor stateful switchover— Active/standby dual supervisor configuration. State and configuration remain constantly synchronized between two Virtual Supervisor Modules (VSMs) to provide seamless and statefu1 switchover in the event of a VSM failure.
The Cisco Nexus 1000V system is made up of the following:
-
Virtual Ethernet Modules (VEMs) running within virtualization servers. These are represented as modules within the VSM.
-
A remote management component, for example. VMware vCenter Server.
-
One or two VSMs running within Virtual Machines (VMs)
System-Level High Availability
The Cisco Nexus 1000V supports redundant VSM virtual machines — a primary and a secondary — running as an HA pair. Dual VSMs operate in an active/standby capacity in which only one of the VSMs is active at any given time, while the other acts as a standby backup. The state and configuration remain constantly synchronized between the two VSMs to provide a statefu1 switchover if the active VSM fails
Single or Dual Supervisors
The Cisco Nexus 1000V system is made up of the following:
-
Virtual Ethernet Modules (VEMs) running within virtualization servers (these are represented as modules within the VSM)
-
A remote management component, for example. VMware vCenter Server.
-
One or two Virtual Supervisor Modules (VSMs) running within Virtual Machines (VMs)
|
|
-
Stateless—Service restarts from the startup configuration
-
Stateful—Service resumes from previous state.
|
-
One active VSM and one standby VSM.
-
The active VSM runs all the system applications and controls the system.
-
On the standby VSM, the applications are started and initialized in standby mode. They are also synchronized and kept up to date with the active VSM in order to maintain the runtime context of “ready to run.”
-
On a switchover, the standby VSM takes over for the active VSM.
|
Network-Level High Availability
The Cisco Nexus 1000V HA at the network level includes port channels and Link Aggregation Control Protocol (LACP). A port channel bundles physical links into a channel group to create a single logical link that provides the aggregate bandwidth of up to eight physical links. If a member port within a port channel fails, the traffic previously carried over the failed link switches to the remaining member ports within the port channel.
Additionally, LACP lets you configure up to 16 interfaces into a port channel. A maximum of eight interfaces can be active, and a maximum of eight interfaces can be placed in a standby state.
For additional information about port channels and LACP, see the
Cisco Nexus 1000V Layer 2 Switching Configuration Guide, Release 4.0
.
Recovering VSMs in an HA Setup after Executing Write Erase
After entering the
write
erase
command on a secondary VSM and bringing up this VSM to rejoin the primary VSM, the primary VSM resets and a cluster outage occurs. The
write erase
command clears the entire configuration except domain-id and system role.
This section contains the following topics to recover VSMs in an HA setup after executing the
write erase
command:
Recovering a Standalone VSM after Executing a Write Erase
You can recover a standalone VSM after executing the
write erase
command.
PROCEDURE
Step 1 Copy the running configuration to the TFTP server. Enter the following command:
copy running-configuration
Step 2 Erase all the configurations in the startup configuration. Enter the following command:
write erase
Step 3 Reload the VSM. Enter the following command:
reload
After the VSM is reloaded, it comes up as a fresh VSM.
Step 4 Configure the domain-id. Enter the following command:
domain id
number
Step 5 Configure the role. Enter the following command:
role name
role-name
Step 6 Set up the initial configuration.
Step 7 Copy the running configuration to the startup configuration from the TFTP server. Enter:
copy running-configuration
Note Ignore all the warnings and error messages.
All the modules are attached.
Step 8 Copy the running configuration to the startup configuration. Enter:
copy running-configuration start-configuration
Recovering an HA Setup VSMs after Executing a Write Erase
You can recover HA setup VSMs after executing the
write erase
command.
PROCEDURE
Step 1 Be sure HA is configured correctly between the primary and secondary VSMs.
Step 2 Copy the running configuration to the TFTP server. Enter the following command:
copy running-configuration
Step 3 Erase all the configurations in the startup configuration. Enter the following command:
write erase
Step 4 Reload the VSM. Enter the following command:
reload
After the VSM is reloaded, it comes up as a fresh VSM.
Step 5 Configure the domain-id on the primary VSM. Enter the following command:
domain id
number
Step 6 Configure the role on the primary VSM. Enter the following command:
role name
role-name
Step 7 Set up the initial configuration.
Step 8 Copy the running configuration from the TFTP server. Enter the following command:
copy running-configuration
Note Ignore all the warnings and error messages.
All the modules are attached.
Step 9 Copy the running configuration to the startup configuration. Enter the following command:
copy running-configuration
Step 10 Configure the domain ID on the secondary VSM. Enter the following command:
domain id
number
Step 11 Configure the role on the secondary VSM. Enter the following command:
role name
role-name
Step 12 When you are prompted to reload, enter
y
.
After the VSM is reloaded, it will start to synchronize as the standby in the HA setup.
Recovering an Individual Secondary VSM in an HA Setup after Executing a Write Erase
You can recover an individual secondary VSM in an HA setup after executing the
write erase
command.
PROCEDURE
Step 1 Be sure that HA is correctly configured between the primary and secondary VSMs.
Step 2 Perform a system switchover, if the secondary VSM is active.
Step 3 After the HA is configured, enter
write erase
All the configurations are erased in the startup-configuration.
Step 4 Reload only the secondary VSM. Enter:
reload module
Step 5 Copy the running configuration to the startup configuration in the primary active VSM. Enter:
copy running-configuration start-configuration
After the secondary VSM is reloaded, it comes up as a fresh VSM.
Step 6 On the secondary VSM, configure the domain-id. Enter the following command:
domain id
number
Step 7 On the secondary VSM, configure the role. Enter the following command:
role name
role-name
Step 8 When you are prompted to reload, enter
y
.
After the VSM is reloaded, it will start to synchronize as the standby in the HA setup.
Recovering an Individual Primary VSM in an HA Setup after Executing Write Erase
You can recover an individual primary VSM in an HA setup after executing the
write erase
command.
PROCEDURE
Step 1 Make sure that HA is configured successfully between primary and secondary VSMs.
Step 2 Perform a system switchover, if the primary VSM is active.
Step 3 After HA is configured, enter the following command:
write erase
All the configurations in the startup-configuration are erased.
Step 4 Reload only the primary VSM. Enter the following command:
reload module 1
Step 5 Copy the running configuration to the startup configuration in the secondary active VSM.
Step 6 Once Primary VSM reloaded, it will come up as fresh VSM.
Step 7 Disable the
Connect
option in the VC to disconnect the control and management communication from the primary VSM
Step 8 On the primary VSM, configure the domain-id. Enter the following command:
domain id
number
Step 9 On the primary VSM, configure the role. Enter the following command:
role name
role-name
Step 10 Skip the initial configuration.
Step 11 Enter the following command:
copy running-configuration start-configuration
Step 12 Power on the primary VSM in the VC.
After the primary VSM is powered on, it will start to synchronize as the standby in the HA setup.
High Availability Troubleshooting Commands
This section lists commands that can be used troubleshoot problems related to High Availability.
To list process logs and cores, use the following commands:
VDC No Module-num Process-name PID Core-create-time ------ ---------- ------------ --- ---------------- 1 1 private-vlan 3207 Apr 28 13:29
-
show processes log [pid
pid
]
n1000V# show processes log VDC Process PID Normal-exit Stack Core Log-create-time --- --------------- ------ ----------- ----- ----- --------------- 1 private-vlan 3207 N Y N Tue Apr 28 13:29:48 2009 n1000V# show processes log pid 3207 ====================================================== Description: Private VLAN Started at Wed Apr 22 18:41:25 2009 (235489 us) Stopped at Tue Apr 28 13:29:48 2009 (309243 us) Uptime: 5 days 18 hours 48 minutes 23 seconds Start type: SRV_OPTION_RESTART_STATELESS (23) Death reason: SYSMGR_DEATH_REASON_FAILURE_SIGNAL (2) <-- Reason for the process abort Last heartbeat 46.88 secs ago System image name: nexus-1000v-mzg.4.0.4.SV1.1.bin System image version: 4.0(4)SV1(1) S25 Exit code: signal 6 (core dumped) <-- Indicates that a cores for the process was generated.
To check redundancy status, use the following commands:
-
show system redundancy status
N1000V# show system redundancy status administrative: primary <-- Configured redundancy role operational: primary <-- Current operational redundancy role Redundancy state: Active <-- Redundancy state of this VSM Internal state: Active with HA standby Redundancy state: Standby <-- Redundancy state of the other VSM Supervisor state: HA standby Internal state: HA standby <-- The standby VSM is in HA mode and in sync
To check the system internal redundancy status, use the following command:
-
show system internal redundancy info
n1000V# show system internal redundancy info domain: 184 <-- Domain id used by this VSM role: primary <-- Redundancy role of this VSM status: RDN_ST_AC <-- Indicates redundancy state (RDN_ST) of the this VSM is Active (AC) status: RDN_ST_SB <-- Indicates redundancy state (RDN_ST) of the other VSM is Standby (SB) degraded_mode: false <-- When true, it indicates that communication through the control interface is faulty Redun Device 0: <-- This device maps to the control interface tx_set_ver_req_pkts: 11590 tx_heartbeat_req_pkts: 442571 rx_heartbeat_rsp_pkts: 442546 <-- Counter should be increasing, as this indicates that communication between VSM is working properly. Redun Device 1: <-- This device maps to the mgmt interface tx_set_ver_req_pkts: 11589 tx_heartbeat_req_pkts: 12 rx_heartbeat_rsp_pkts: 0 <-- When communication between VSM through the control interface is interrupted but continues through the mgmt interface, the rx_heartbeat_rsp_pkts will increase.
To check the system internal sysmgr state, use the following command:
-
show system internal sysmgr state
N1000V# show system internal sysmgr state The master System Manager has PID 1988 and UUID 0x1. Last time System Manager was gracefully shutdown. The state is SRV_STATE_MASTER_ACTIVE_HOTSTDBY entered at time Tue Apr 28 13:09:13 2009. The '-b' option (disable heartbeat) is currently disabled. The '-n' (don't use rlimit) option is currently disabled. Hap-reset is currently enabled. Watchdog checking is currently disabled. Watchdog kgdb setting is currently enabled. The trace mask is 0x00000000, the syslog priority enabled is 3. The '-d' option is currently disabled. The statistics generation is currently enabled. cardstate = SYSMGR_CARDSTATE_ACTIVE . cardstate = SYSMGR_CARDSTATE_ACTIVE (hot switchover is configured enabled). Configured to use the real platform manager. Configured to use the real redundancy driver. Redundancy register: this_sup = RDN_ST_AC, other_sup = RDN_ST_SB. Remote addresses: MTS - 0x00000201/3 IP - 127.1.1.2 Module online notification received. Local super-state is: SYSMGR_SUPERSTATE_STABLE Standby super-state is: SYSMGR_SUPERSTATE_STABLE Swover Reason : SYSMGR_SUP_REMOVED_SWOVER <-- Reason for the last switchover Total number of Switchovers: 0 <-- Number of switchovers >> Duration of the switchover would be listed, if any. Total latency: 0 Max latency: 0 Total exec: 0 Max exec: 0
To reload a module, use the following command:
This command reloads the secondary VSM.
Note Issuing the reload command without specifying a module will reload the whole system.
To attach to the standby VSM console, use the following command.
The standby VSM console is not accessible externally, but can be accessed from the active VSM through the
attach module
module-number
command.
This command attaches to the console of the secondary VSM.