Time taken to run, "copy running-config startup-config"

[msgforsunil]

Hello All,

How can we predict the time taken to run the below command? 

"copy running-config startup-config"

Is the complete running config copied onto startup config?

OR

Are the only changed ones in running-config are updated/added/removed to/from startup config?

Thank you,

Sunil Kumar

[Leo Laohoo]

Sunil, 

Not easy to determine how long does it take to save the config.  This is because I don't know what platform you're talking about, what is your IOS version, how long is your configuration, etc.

But in Catalyst 2K and 3K, it normally takes less than 4 seconds to save the config.  Some cases like VSS switches can take up to 20 seconds.  

[msgforsunil]

Leo,

Its  c7600 router, with version as 12.2.  Do you want to run some command to state how long the configuration is?  If yes, please let me know.

By the way,  can you please answer to the below?

Is the complete running config copied onto startup config?

OR

Are the only changed ones in running-config are updated/added/removed to/from startup config?

Thank you.

[darkdesire.cisco]

complete running config gets copied to startup config. there is no incremental backup. i guess total time taken also should be dependent on the current CPU and memory load. Ideally. I have never seen this time exceeding more than 30 seconds. In nexus switches some time it took around 40 seconds.