booting from flash cards on 6509, vlan.dat file

Unanswered Question
Feb 10th, 2009

I have a 6509 and I currently am booting from the IOS on disk0.

Disk0 also has the vlan.dat file on it.

I would like to upgrade the IOS on the 6509, but keep the IOS image on disk0.

My plan is to have disk0 ejected and add disk1 to the boot list.

If I have any problems with the IOS on disk1, I will just push disk0 back in and boot from it.

My questions are:

What tells the 6509 where to read the vlan.dat file upon boot?

For example, if i want to laod an image onto disk1 and boot from there, do I need a copy of the vlan.dat on disk1 also?

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Overall Rating: 5 (2 ratings)
Jon Marshall Tue, 02/10/2009 - 16:17


The vlan.dat on a 6500 is stored in const_nvram. Do a "dir const_nvram" and see if you see the vlan.dat. Have a look at this doc which covers vlan.dat file on 6500 running IOS -

By the way you don't need to eject disk0 you can just change your "boot system flash ...." statement in your running config so the first one is disk1 ie.

boot system flash disk1:

boot system flash disk0:


wilson_1234_2 Tue, 02/10/2009 - 16:45

Thanks jon,

So currently the only boot statement is pointing to the image on disk 0,

So are you saying to remove that and then add both lines in the order of



install both disks,

if I run into problems, eject disk1 holding the newer image and reboot to disk0?

Jon Marshall Tue, 02/10/2009 - 16:50


"So are you saying to remove that and then add both lines in the order of



Yes, absolutely. It also protects against a bad or corrupt image ie. you know disk0: imahe works because that is the one you are booting with at present. So copy that "boot system flash disk0:" line to notepad, add the disk1 line above in notepad, remove the existing line from the running-config pointing to disk0: and then paste back in the 2 lines from notepad.



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