Why does RME archive the VLAN.DAT files?

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Oct 16th, 2008

RME goes to a lot of trouble to archive VLAN.DAT files from IOS switches, over time creating many thousands of files on the server. I have often wondered why. Is there any use for an archived VLAN.DAT file?

I have this problem too.
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Joe Clarke Thu, 10/16/2008 - 06:35

Yes. This file is needed for disaster recovery on switches which require it. Without restoring vlan.dat, you would not have any vlans if you had to restore the config to your switch.

dave.bird Fri, 10/17/2008 - 02:38

Absolutely, which is also why it is nice to have the latest running config in the shadow directory to push into a new switch. But why do I need 607,725* archived versions? Disaster recovery is always about the latest running configurations, never about the state of the switch 3 years ago. You might argue that there is no harm storing them but have you done a database restore recently? It takes hours to restore them all.

* Total number archived on our server across all 500 or so switches managed for the last 3 years.

Joe Clarke Fri, 10/17/2008 - 07:31

One of the problems with vlan.dat is that it is opaque. There is no way to tell if vlan.dat really got changed. We can't simply do comparisons like we do with the running and startup configs. Therefore, we err on the side of caution, and archive vlan.dat every time the running config is fetched.

If your switches are in VTP transparent mode, and they are running new enough code, vlan.dat is obsolete, and can be deleted. The VTP and VLAN config will be in the running config itself.


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