Wednesday, July 21, 2010

Nexus 1000v bug - Three ways to check VSM HA health

If you are using Nexus 1000v, more than likely you have set up VSM high availability. To ensure system stability and gain the true benefit of HA, check if VSM HA is truly synchronized. Don’t stop when you see 2 supervisor modules. Otherwise you may be caught at the worst time of a failure scenario, and found out there is no HA, and you have to deal with a bug, even configuration loss.

Specifically, check after initial setup, and after system operations such as VSM reload. There is a bug, CSCtg46327, fixed in 4.0(4)SV1(3a). It prevents VSM active and standby to synchronize. Standby continues to come up and down in attempts to do so.

You can check for this bug and other potential VSM HA problem using these methods:

1. “show module” output affected by the bug, module 2 should show “VSM, Nexus 1000V, ha-standby”, instead of “powered-up”:

vsm# sh module
Mod Ports Module-Type Model Status
--- ----- -------------------------------- ------------------ ------------
1 0 Virtual Supervisor Module Nexus1000V active *
2 0 Supervisor/Fabric-1 powered-up
5 248 Virtual Ethernet Module NA ok
6 248 Virtual Ethernet Module NA ok
7 248 Virtual Ethernet Module NA ok

2. “show svs neighbor” list standby VSM MAC as a “VEM”, which is incorrect. It should be type VSM:
vsm# sh svs nei
Active Domain ID: 91
AIPC Interface MAC: 0050-56b4-52bb
Inband Interface MAC: 0050-56b4-3fc1

Src MAC Type Domain-id Node-id Last learnt (Sec. ago)
0050-56b4-5eb5 VEM 0 ffffffff 0.00
0002-3d43-8504 VEM 901 0502 160591.40
0002-3d43-8505 VEM 901 0602 160591.30
0002-3d43-8506 VEM 901 0702 160230.70

3. “show system redundancy status” shows operational mode “none”, which should be HA:

vsm# sh sys red stat
Redundancy role
administrative: primary
operational: primary

Redundancy mode
administrative: HA
operational: None

This supervisor (sup-1)
Redundancy state: Active
Supervisor state: Active
Internal state: Active with warm standby

Other supervisor (sup-2)
Redundancy state: Standby
Supervisor state: HA standby
Internal state: HA standby

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