As title.

How much time is needed to swtich the IP from a Linode to another Linode in the same datacenter?
seconds, minutes, hours, how much?

Will I have downtime during this process, I can have a maximum downtime of 60 seconds, than problems starts and I want to avoid problems if possible?

It takes however long your linodes take to shutdown and boot up.

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this is true but how much time is needed to switch the IP from the two node?

seconds, minutes or hours?

I would say less than 2 minutes for your linodes to reboot after making the necessary changes in the Linode Manager. Though I haven't timed it myself. I'm sure your millage will very.

--
Travis

It's instant..hence the time required is how long it takes you to shutdown and boot up.

_________________
Paid support
How to ask for help
1. Give details of your problem
2. Post any errors
3. Post relevant logs.
4. Don't hide details i.e. your domain, it just makes things harder
5. Be polite or you'll be eaten by a grue