Cannot write to const_nvram 6509 - Sup720

Unanswered Question
May 23rd, 2008
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My IOS: s72033-ipservicesk9-mz.122-18.SXF12.bin

I cannot do a: "copy tftp const_nvram:vlan.dat"

After a successful tftp transfer, the switch immediately responds with an error to the effect of , "cannot write to const_nvram".

This command works with this IOS, "s72033-jk9sv-mz.122-18.SXD7b.bin"

Any help would be greatly appreciated!



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lamav Fri, 05/23/2008 - 08:26
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In order to restore the vlan.dat file, complete these steps:

Copy the vlan.dat file into the device's NVRAM from a TFTP server or an external PCMCIA card.

copy tftp: const_nvram:

notice no vlan.dat file name present...

Reload the switch, as vlan.dat is read only during the booting process.



gilbert.jason Fri, 05/23/2008 - 08:58
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Tried that and still have the same problem

Here is what I typed.

copy ttp: const_nvram:

I got:

"%Warning: There is a file already existing with this name Do you want to over write? [confirm]

Cannot copy from vlan.dat to vlan.dat"

ita_hsieh Tue, 10/19/2010 - 23:31
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Dear Jason:

   Did you happen to solve the problem? I am facing the same issue. Thanks.

FlorianBerthelot Fri, 12/30/2011 - 05:29
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Did you manage to solve this issue ? I am having the same, i tried with a

erase const_nvram before the reload but with no luck.

Thanks in advance

amikat Sat, 12/31/2011 - 01:33
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Can you please post the "dir const_nvram:" command output.



FlorianBerthelot Tue, 01/03/2012 - 00:54
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Hello Amikat,

Thanks for your reply, dir const_nvram says that vlan.dat

1     -rwx     0          vlan.dat

I also did a

Chassis#erase const_nvram

Erasing the const_nvram filesystem will remove all configuration files! Continue? [confirm]


Erase of const_nvram: complete



but no chances, i get :

User Access Verification



Chassis#copy bootflash:vlan.dat const_nvram:vlan.dat

Destination filename [vlan.dat]?

%Warning:There is a file already existing with this name

Do you want to over write? [confirm]

Cannot copy from vlan.dat to vlan.dat


Thanks you in advance if you have any ideas...

best regards

amikat Tue, 01/03/2012 - 01:49
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Thanks for the reply.

Can you please try to use the command "delete const_nvram:vlan.dat" instead of "erase ..." and if succeed reload the switch and try again the "copy ..." command and see if there is any progress.

Best regards,


FlorianBerthelot Tue, 01/03/2012 - 01:52
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Hi again, same issu when I use the delete command... I will make some tests today and let you know, I did follow the Cisco procedure, i do have all expected output (reset of the VLAN & VTP configuration) but still no way to copy the file.

I will keep you informed, regards

amikat Tue, 01/03/2012 - 02:18
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Thanks for the reply.

What is you vtp status? I would suggest to set it to "client" before deleting the vlan.dat.

Best regards,


FlorianBerthelot Fri, 01/06/2012 - 07:42
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I tried to change the vtp status, no chance. I did upgrade the chassis to the same version as the originate vlan.dat, and that worked fine.

According to the TAC, this is not a software version issue, bug this might be bug


VSL : Unable to replace vlan.dat file with Sierra image.


Unable to replace vlan.dat file


When attempting to copy vlan.dat file from disk0: to nvram: the copy is blocked and the console displays the error message "Cannot copy from vlan.dat to vlan.dat"


Downgrade to 12.2(18)SXF7 or upgrade to a release that integrates the fix.


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