3850stack Upgrade IOS without downtime

[AlexandrosMavridis]

Hi all,

i want to update a 3850stack without to have an downtime, is there any solution? Because so far i know if i reboot first the primary then we have a firmware  mismatch.

Thanks a lot.

[balaji.bandi · Accepted solution]

there is no solution available for now without downtime upgrade for the Stack upgrade.

Stack required to reboot after upgrade.

[AlexandrosMavridis]

of course we need to restart the switch the point is if we can restart the first member and then the second so we can avoid the downtime but we need also to be sure that we will not have the mismatch problem, i dont know if its possible  

[Leo Laohoo · Accepted solution]

Not possible.
And depending on what firmware you want to reach to, it will take between 6 to 24 minutes.

[AlexandrosMavridis]

yes i know how much time needed i made this manytimes before but now is in production in area that we can not have an outage.

Thanks a lot.

[Martin L]

1. you add new switch with new version, enable install mode with software expand.
2. configure remaining switches to download version from new switch ; software auto-upgrade -I think is command
3. reboot one by one , waiting until previous one is done. then reboot next one.
4. older switches should download software from new switch.

[jonkimsr]

Have enough space in the RACK. 
Install new stack. Move ports.