How to Remove a Flash Partition on a Cisco 2500 Series Router

If you’re building your CCIE lab and you’ve just installed a second 8MB flash stick in your 2500 series router, chances are you are booting up with two separate flash partitions of 8MB each, instead of the preferred 16MB single partition.

If you’d like to fix this and merge them into one large partition as I’m sure you do, here’s how to do so:

Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#config-register 0x2101
Router(config)#end
Router#show version

Ensure that it says this at the bottom of the “show version”:

Configuration register is 0x2102 (will be 0x2101 at next reload)

Reload the router and it will ask you if you want to save the configuration settings, state YES, and it should boot in ROM memory (boot mode).

Router(boot)#show flash

You should see something like this but in your case it will be 2 or more partitions with the IOS on one and possibly something else on the other partition(s).

System flash directory:
File Length Name/status
1 14598352 /c2500-ik8os-l.122-19a.bin
[14598416 bytes used, 2178800 available, 16777216 total] 16384K bytes of processor board System flash (Read/Write)
Router(boot)#


Now, type this out:

Router(boot)#erase flash

It will ask you which partition to erase. Erase the one WITHOUT the IOS on it, usually its number 2. Repeat that for all the partitions except the one with the IOS on it.

Then type:

Router(boot)#config t
Router(boot)(config)#no partition flash
Router(boot)(config)#exit

After which:

Router(boot)#show version
And verify the flash partition has been deleted.

Once the flash partition has been eliminated, change the config-register to 0x2102:

Router(boot)#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(boot)(config)#config-register 0x2102
Router(boot)(config)#end
Router(boot)#show version

And again checking the last line to see if it states the config register will be 0x2102 at next reload by the “show version” command. Reload and it should come online with no partitions:

Router(boot)#reload

It will ask you if you want to save the settings, state YES again.
You’re done!