deleting IOS from flash in production routers to make room for the new IOS

Answered Question
May 4th, 2008

I have some 2821 rtrs which will be getting an IOS upgrade from "c2800nm-spservicesk9-mz.124-3g.bin" to "c2800nm-adventerprisek9-mz.124-18.bin"

There is not enough space in flash to hold the new IOS and the current IOS.

Is it possible to delete the current IOS from flash and load the new IOS?

I have this problem too.
0 votes
Correct Answer by Amit Singh about 8 years 6 months ago

Hi,

As this is your production router and just to be on a safer side, you can also have the IOS loaded on a TFTP and have your router boot via the network TFTP. This will you will have your router up and running incase of something doesnot work while formating the flash and loading the IOS.

Router(config)# boot system tftp IOS filename tftp server ip address - boot from a TFTP server

regards,

-amit singh

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phretbored Sun, 05/04/2008 - 22:21

Right on that makes sense as I have done it before...but not in a good while...just wanted to measure twice and cut once!

Actually I left out something in my initial post.

In what version of IOS did upgrading in this manner become available?

In older versions of IOS was it not possible to upgrade in this way?

If there is a cutoff approx what IOS version would be too old to upgrade this way?

Paolo Bevilacqua Sun, 05/04/2008 - 22:44

Hi, this does not depend on the IOS version and never did. Just delete old IOS and copy the new one.

Also, IOS never requires progressive upgrades.

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Correct Answer
Amit Singh Sun, 05/04/2008 - 22:55

Hi,

As this is your production router and just to be on a safer side, you can also have the IOS loaded on a TFTP and have your router boot via the network TFTP. This will you will have your router up and running incase of something doesnot work while formating the flash and loading the IOS.

Router(config)# boot system tftp IOS filename tftp server ip address - boot from a TFTP server

regards,

-amit singh

Richard Burts Mon, 05/05/2008 - 03:36

Mark does remember correctly that there was a time when you could not just erase the image and load a new image while the router continued to run. But it was platform based and not version of IOS based. There were some routers that ran the image from flash rather than from RAM. They primary example of this was the 2500 routers which actually had to boot into rommon to load a new image.

There have not been any routers with this restriction in quite a while. So Mark should be pretty safe in erasing the image and copying a new image. There is a bit of exposure in this process - if something happens in the interval between when the old image is erased and the copy of the new image is completed then there is a problem. The suggestion from Amit is a way to provide a bit of a safety net. It requires a bit more effort than just erase the old image, copy the new image, reboot - but it does provide a method that does not leave you exposed. Especially if the router is remote it might be worth it.

HTH

Rick

phretbored Mon, 05/05/2008 - 08:56

Thanks everyone for your comments.

I appreciate the input and helpful suggestions.

I will follow the method that Amit pointed out.

GLTA.

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