How to unbrick a 2960X after interrupting an auto-update

[William750]

I connected a switch that had an older IOS to an active stack hoping the auto-update from the master stack would take care of the IOS upgrade for me. But it was Friday evening and I wanted to go home, so even after almost an hour of repetitiously typing "show switch" but still seeing "version mismatch", I unplugged the new stack member and went home. Monday morning I brought the switch to my desk and connected via the blue console cable and saw that the IOS on the flash: was missing and it couldn't boot past rommon mode. After raising the BAUD and loading an updated IOS using xmodem, I then told rommon to boot the new IOS. All seemed good at first, but after a self restart it started looking for the old c2960x-universalk9-mz.150-2a.EX5.bin IOS again. I couldn't get the switch to see the new 152-7.E2.bin I loaded onto the flash:

The fix:

Despite the new IOS on the flash: it was like there was some other instruction the switch was following. I guess I just wasn't patient enough and interrupted the auto-update, causing some form of corruption. I then decided to format the entire flash: and restart from scratch (in rommon mode, "format flash:"). After doing xmodem again and booting to the IOS from rommon mode, I got the switch to boot fine now.

Though there are some strange things still occurring in the switch. When plugging in the switch, it still looks for 150-2a.bin, fails, then looks for 152-7.E2.bin and succeeds in booting up. I thought I formatted the flash:? Also, when doing a "sh swi" it still sees itself as the 4th switch in a stack despite it still being on my desk and despite me formatting the flash: entirely. I'll even to a "sh run" and see the ports as "int g4/0/X". Wouldn't have formatting the flash: cleared all of those settings I implemented while waiting for auto-update to finish? Is there another storage medium besides flash: and rommon that stores some sort of configuration data? Any insight would be much appreciated. 

[Leo Laohoo · Accepted solution]

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@William750 wrote:

Also, when doing a "sh swi" it still sees itself as the 4th switch in a stack despite it still being on my desk and despite me formatting the flash: entirely. I'll even to a "sh run" and see the ports as "int g4/0/X". 

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Try this: 

conf t
 switch 4 renumber 1
end

Reboot the switch.  No need to save the config.

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@William750 wrote:

When plugging in the switch, it still looks for 150-2a.bin, fails, then looks for 152-7.E2.bin and succeeds in booting up.

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Post the complete output to the command "sh boot".

[William750]

Thank you for getting back to me! 

I did a 'show boot' and saw that the boot parameters were pointing to an out of date IOS:

BOOT path-list : flash:/c2960x-universalk9-mz.150-2a.EX5/c2960x-universalk9-mz.150-2a.EX5.bin 

Within 'conf t' I used "boot system flash:c2960x-universalk9-mz.152-7.E4.bin" and now it always looks for the right IOS. Thank you for pointing me in the right direction!

Also, re-numbering the switch won't be necessary as I plan on re-introducing it to the stack later this week. I was more curious as to why the switch remembered its number after I formatted the flash: in rommon. I see that you said there is no need save the config, which tells me that switch number info is saved somewhere else. It can't be flash: because I formatted that. Is there another storage medium in the switch?

Thank you again for your help

[Leo Laohoo]

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@William750 wrote:

 Is there another storage medium in the switch?

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I believe it is stored in the NVRAM.