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New Member

Will WebNS 7.5 auto fallback if new code failed to boot?


I'm preparing for WebNs upgrade from 7.4 to 7.5 to 8.2

And change will be done remotely.

My question is, what will happen if the new code doesn't boot up after we reboot the CSS?

Will it auto fall back to the previous working code?

Thank you.

Everyone's tags (2)

Re: Will WebNS 7.5 auto fallback if new code failed to boot?


It would depend on where in the upgrade process it fails.  If it helps, we rarely hear of this kind of problem as the CSS is quite stable, including the upgrade process.

I encourage you to perform the upgrade using the Upgrade Script.  If the upgrade fails, then you should be able to recover by using the Manual Upgrade process.

BTW, the WebNS 7.50 software release is now End-of-Life and no longer supported by engineering.  Since you are upgrading, I would strongly recommend that you upgrade to the latest release of 8.10 or 8.20.

Hope this helps,


New Member

Re: Will WebNS 7.5 auto fallback if new code failed to boot?


I'm sorry. The upgrade is from 7.5 to 8.2. I missed look it.

The point where the upgrade process fail is assuming it happen after the following steps:

1.Make new code as primary boot

     : (config-boot)#primary boot-file

2.Save the configuration

     : save_config

3.Reboot the CSS

     : reboot



{ Boot fail }

Will the CSS auto fallback to the previous WebNS if this problem happened?

The reason I'm asking is because I need to setup a backout plan for this upgrade.

Change will be done remotely and cross country. So it's not possible to have a direct physical interface with the box.

Thank you. 


Re: Will WebNS 7.5 auto fallback if new code failed to boot?


Good to see your going to 8.20 software.

I can't say for sure whether or not your CSS will fall back to the original image, although my suspicion is that it will not.  I will assume that your CSS is in a redundant configuration consisting of a pair of CSS.  Please correct me if I'm wrong.  You can alway upgrade the standby CSS, and make sure if boots up OK on the new code.  Then you can fail over to it, while you upgrade the second CSS.  This way, you would always be upgrading the standby CSS, so traffic should not be impacted, even in the event of a boot failure.  Then you can recover the standby that didn't boot properly while the master CSS is safely handling production traffic.

Also, I would recommend using the upgrade script rather than the manual upgrade process, especially if you have any custom user accounts and/or custom scripted probes.  Another good idea as a backup plan is to temporarily (or permanently) arrange for console access to the two CSS during the upgrade process, just in case it is needed, as you are doing the upgrade remotely.