Cisco 6509 software upgrade from 12.2(33)SXI12 to 15.1(2)SY10

[Alexander Yug]

Hello everyone. I have Cisco 6509-E with two (active and hot) supervisors SUP720-3B running IOS version 12.2.(33)SXI12.

I need to upgrade to IOS version 15.1(2)SY10.

Is there any way to do it with zero downtime?

I followed instructions from this article

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/71585-cat6k-red-supeng-swimg-upg.html#native

but after I've completed step 10 standby supervisor booted in rommon mode.

It is possible to boot standby supervisor with the previous IOS using the following command

boot bootdisk:s72033-adventerprisek9_wan-mz.122-33.SXI12.bin

[Iulian Vaideanu]

There's no way to upgrade with zero downtime (at the very least the line cards would have to get reset when moving to a different version, which takes a couple of minutes).

If the standby got stuck in rommon it should be possible to manually boot it (via console) to whatever IOS it has available...

[Alexander Yug]

In this case I will scheduled upgrade within maintenance window.

Thank you.