Cisco Nexus 1000V Troubleshooting Guide, Release 4.0(4)SV(1)

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Updated:
April 10, 2009

Chapter: Troubleshooting High Availability


High Availability

This chapter describes how to identify and resolve problems related to High Availability.

This chapter includes the following sections:

•Information About High Availability

•Problems with High Availability

•High Availability Troubleshooting Commands

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)

Single VSM Operation
Dual VSM Operation

•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.

Problems with High Availability

Symptom
Possible Causes
Solution

The active VSM does not see the standby VSM.

Roles are not configured properly.

•Check the role of the two VSMs using the show system redundancy status command.

1. Confirm that the roles are the primary and secondary role, respectively.

2. If needed, use the system redundancy role command to correct the situation.

3. Save the configuration if roles are changed.

Network connectivity problems.

•Check the control and management VLAN connectivity between VSM at the upstream and virtual switches.

If network problems exist:

1. From the vSphere client, shut down the VSM, which should be in standby mode.

2. From the vSphere client, bring up the standby VSM after network connectivity is restored.

The active VSM does not complete synchronization with the standby VSM.

Version mismatch between VSMs.

•Check that primary and secondary VSM are using the same image version using show version command.

If the active and standby VSM software versions differ, reinstall the secondary VSM with the same version used in the primary.

Fatal errors during gsync process.

•Check the gsyncctrl log using the show system internal log sysmgr gsyncctrl command and look for fatal errors.

Reload the standby VSM using the reload module module-number command, where module-number is the module number for the standby VSM.

The standby VSM reboots periodically.

The VSM has connectivity only through the management interface.

•When a VSM is able to communicate through the management interface, but not through the control interface, the active VSM detects the situation and resets the standby VSM to prevent the two VSMs from being in HA mode and out of sync.

•Check the output of the show system internal redundancy info command and verify if the degraded_mode flag is set to true.

Check control VLAN connectivity between the primary and secondary VSMs.

VSMs have different versions.

Enter the debug system internal sysmgr all command and look for the active_verctrl entry that indicates a version mismatch, as the following output shows:

2009 May 5 08:34:15.721920 sysmgr: active_verctrl: Stdby running diff version- force download the standby sup.

Isolate the standby VSM and boot it.

Use the show version command to check the software version in both VSMs.

Install the image matching the Active VSM on the standby.

Both VSMs are in active mode.

Network connectivity problems.

•Check for control and management VLAN connectivity between the VSM at the upstream and virtual switches.

•When the VSM cannot communicate through any of these two interfaces, they will both try to become active.

If network problems exist:

1. From the vSphere client, shut down the VSM, which should be in standby mode.

2. From the vSphere client, bring up the standby VSM after network connectivity is restored.

Different domain IDs in the two VSMs

Check domain value using show system internal redundancy info command.

If needed, update the domain ID and save it to the startup configuration.

•Upgrading the domain ID in a dual VSM system must be done following a certain procedure.

–Isolate the VSM with the incorrect domain ID so that it cannot communicate with the other VSM.

–Change the domain ID in the isolated VSM, save configuration, and power off the VSM.

–Reconnect the isolated VSM and power it on.


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:

•show cores 

n1000V# show cores

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

======================================================

Service: private-vlan

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


PID: 3207 

Exit code: signal 6 (core dumped) <-- Indicates that a cores for the process was 
generated.


CWD: /var/sysmgr/work

...

To check redundancy status, use the following commands:

•show system redundancy status 

N1000V# show system redundancy status 

Redundancy role

---------------

      administrative:   primary <-- Configured redundancy role

         operational:   primary <-- Current operational redundancy role


Redundancy mode

---------------

      administrative:   HA

         operational:   HA


This supervisor (sup-1)

-----------------------

    Redundancy state:   Active <-- Redundancy state of this VSM

    Supervisor state:   Active

      Internal state:   Active with HA standby                  


Other supervisor (sup-2)

------------------------

    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 

My CP:

  slot: 0

  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)

  state:  RDN_DRV_ST_AC_SB

  intr:   enabled

  power_off_reqs: 0

  reset_reqs:     0

Other CP:

  slot: 1

  status: RDN_ST_SB <-- Indicates redundancy state (RDN_ST) of the other VSM is 
Standby (SB)

  active: true

  ver_rcvd: true

  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

  name: ha0

  pdev: ad7b6c60

  alarm: false

  mac: 00:50:56:b7:4b:59

  tx_set_ver_req_pkts:   11590

  tx_set_ver_rsp_pkts:   4

  tx_heartbeat_req_pkts: 442571

  tx_heartbeat_rsp_pkts: 6

  rx_set_ver_req_pkts:   4

  rx_set_ver_rsp_pkts:   1

  rx_heartbeat_req_pkts: 6

  rx_heartbeat_rsp_pkts: 442546 <-- Counter should be increasing, as this indicates 
that communication between VSM is working properly.

  rx_drops_wrong_domain: 0

  rx_drops_wrong_slot:   0

  rx_drops_short_pkt:    0

  rx_drops_queue_full:   0

  rx_drops_inactive_cp:  0

  rx_drops_bad_src:      0

  rx_drops_not_ready:    0

  rx_unknown_pkts:       0

Redun Device 1: <-- This device maps to the mgmt interface

  name: ha1

  pdev: ad7b6860

  alarm: true

  mac: ff:ff:ff:ff:ff:ff

  tx_set_ver_req_pkts:   11589

  tx_set_ver_rsp_pkts:   0

  tx_heartbeat_req_pkts: 12

  tx_heartbeat_rsp_pkts: 0

  rx_set_ver_req_pkts:   0

  rx_set_ver_rsp_pkts:   0

  rx_heartbeat_req_pkts: 0

  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.

  rx_drops_wrong_domain: 0

  rx_drops_wrong_slot:   0

  rx_drops_short_pkt:    0

  rx_drops_queue_full:   0

  rx_drops_inactive_cp:  0

  rx_drops_bad_src:      0

  rx_drops_not_ready:    0

  rx_unknown_pkts:       0

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.



        Debugging info:


The trace mask is 0x00000000, the syslog priority enabled is 3.

The '-d' option is currently disabled.

The statistics generation is currently enabled.



        HA info:


slotid = 1    supid = 0

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.

EOBC device name: eth0.

Remote addresses:  MTS - 0x00000201/3      IP - 127.1.1.2

MSYNC done.

Remote MSYNC not done.

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.


        Statistics:


Message count:           0

Total latency:           0              Max latency:             0

Total exec:              0              Max exec:                0

To reload a module, use the following command:

•reload module 

n1000V# reload module 2

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.

•attach module

The standby VSM console is not accessible externally, but can be accessed from the active VSM through the attach module module-number command. 

n1000V# attach module 2

This command attaches to the console of the secondary VSM.

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