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Highlighted
Cisco Employee

How to manually switchover HA state

 

Hi Experts,

 

 

I am Yoichi Kobayashi, working on the NTTE vMS project in Japan.

 

I am testing NSO HA with 2 nodes.

 

 

I have a question, how to manually switch over HA state.

 

 

When I want to switch the roles of the original master-node and the original slave-node opposite with minimum downtime,

 

what is the best operational procedure?

 

 

I have already tried 2 ways.

 

==========

 

The original master-node: NSO-m

 

The original slave-node: NSO-s

 

failure limit: 10

 

interval: 4 sec

 

 

  1. No.1:

 

-(Operating NSO-s CLI) request ha commnads role-override role master

 

and then

 

-(Operating NSO-m CLI) request ha commnads role-override role slave

 

 

  1. No.2:

 

-(Operating NSO-m CLI) request ha commnads role-override role slave

 

==========

 

 

When I did No.1, Master/Slave switched quickly.

 

 

When I did No.2, NSO-s became the master after 40 sec with the alarm.

 

Also the following message appeared.

 

===

 

*** ALARM node-failure: HA connection lost. 'NSO-s' transitioning to HA MASTER role. When the problem has been fixed, role-override the old MASTER to SLAVE to prevent config loss, then role-revert all nodes. This will clear the alarm.

 

===

 

It looks just failing over happend.

 

 

If you need more info, please ping me.

 

Any comment like a consideration is appriciated.

 

 

Best regards,

 

Yoichi

 

4 REPLIES 4
Highlighted
Cisco Employee

Re: How to manually switchover HA state

 

We are using role revert for switching back roles to configured values. Prepare commands on both nodes and then first issue it on current master and then on current slave.

 

 

But we never measured switchover times, usually we were glad it switched back successfully. IMHO it should be done during maintenance window anyhow, so I guess customer could live with service being impaired during that minute or so.

 

 

BR,

 

Bostjan

 

Highlighted
Cisco Employee

Re: How to manually switchover HA state

 

Hi Bostjan,

 

 

Thank you for your comment.

 

 

Prepare commands on both nodes and then first issue it on current master and then on current slave.

 

 

There is a document which says about the order, it seems issue the command on new master first, and then on new slave.

 

 

deployment_guide.pdf p.g 20 (‘ncs-4.2-tailf-hcc-4.0.4.tar.gz’ contains it)

 

https://software.cisco.com/download/release.html?mdfid=286307825&softwareid=286283941&release=4.2&relind=AVAILABLE&rellifecycle=&reltype=latest

 

 

That is why I thought the way No.1 was what I supposed to do when I wanted to change the roles temporary.

 

(e.g. in the situation that the original master needs maintenance)

 

 

Best regards,

 

Yoichi

 

Highlighted
Cisco Employee

Re: How to manually switchover HA state

 

I see in the doc. It seems strange to me because at one point, before role revert on configured slaves, both NSOs are masters. But if that is the official way, I would use it, if it works of course…. I was looking at the older HA deployment guide and the steps were in a different order.

 

 

Not sure if you have to worry about maintenance on the configured master node. Slave takes over automatically if master is lost. Then you have the hurdle to bring master back, start as slave and above role revert thing…

 

 

BR,

 

Bostjan

 

Highlighted
Cisco Employee

Re: How to manually switchover HA state

 

Hi Bostjan,

 

 

Thank you for replying.

 

 

It seems strange to me because at one point, before role revert on configured slaves, both NSOs are masters.

 

 

  • I think so too. I set VIP for HA so both NSOs have the VIP when role revert on configured master before slave.
    Does anyone know whether or not it is ok?

 

 

Best regards,

 

Yoichi

 

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