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Command debate

Discussion in 'Other Cisco Equipment' started by ifican, Jul 23, 2007.

  1. ifican

    ifican Network Guru Member

    At work we get into goofy fun little debates about everything, the one this morning is: What is the difference between copy run start and write mem. I am from the standpoint that there is no difference except for the fact write mem is allegedly to be written out of code. My cube mate swears there is a difference and without going into to what he said at this point, I have through the red flag (review). So anyone care to take a stab at this one, but please be ready to backup with documentation.

  2. t4thfavor

    t4thfavor Network Guru Member

    I would say that since they all exist, they must be different, since nobody ever writes code that re-invents the wheel.

    This is the only explanation you need:)
  3. ifican

    ifican Network Guru Member

    Well this is true, but basically alot of code has been merged since cisco has aquired many different companies along its journey. I have never known of a difference between the 2, you can use either one to accomplish the same thing and cisco has stated many times get out of the habit of using write mem because it is not going to be supported moving forward. The debate continues strong here in the office and no one has yet come up with an answer.
  4. t4thfavor

    t4thfavor Network Guru Member

    I bet its just an older way of doing something, and is now deprecated. (discontinued in future releases)
  5. kspare

    kspare Computer Guy Staff Member Member

    it's the same thing... copy run star wri me it's no different than copy run tftp copy star tftp or write net

    Good on ya for being productive at work ;)
  6. ifican

    ifican Network Guru Member

    You know that is my answer as well, though he swears that he read somewhere copy run start does something with other files like vlan.dat and such where write mem only copies the config. I countered that argument but he still swears that theres a difference.

    Productive with this one yes as it is work related, but the longest running debate is whether a cheeto is infact a chip. Now how to work that into work productivity is beyond me.
  7. kspare

    kspare Computer Guy Staff Member Member

    maybe this will help.

    Write mem was for older IOS, copy run star is the new way to do it, write mem will be written out....

    copy running-config startup-config - copies saved config in running config (RAM) to NVRAM or "write memory" for IOS under ver.11
  8. eric_stewart

    eric_stewart Super Moderator Staff Member Member

    They do the same thing. Here's how it works:

    The write command writes "to" stuff:
    eg: write <to> net ...writes to the net (a tftp server)
    write <to> mem ....writes to memory (NVRAM)

    The *only* thing that is being written "from" is the dynamic (ie: running) configuration in memory. It's a stupid command (thus Cisco's reason for deprecating it some day....) because it makes no intuitive sense. The source that you're copying from is inferred rather than stated. You *do* save a few keystrokes if you're lazy but that's its sole difference. Also Cisco's own engineers (there's a supertanker that take a long time to change course!) have been doing it this way for years and they are highly resistant to change.

    The copy command (thanks Bill Gates) makes more intuitive sense. Just like M$, you're copying from <something> to <something else>
    ....copy running-config startup-config means your copying the dynamic configuration from RAM to the standard, backup file name "startup-config" which is in NVRAM on an IOS router.

    BTW, don't even think of using the write command in a CCNA exam. It's the wrong answer 100% of the time.

  9. eric_stewart

    eric_stewart Super Moderator Staff Member Member

    I would say that since I have a twin brother (I do, BTW), and we both exist, we must be different since God would never re-invent the wheel. This is the only explanation you need :)

    Of course my mother couldn't even tell us apart.

  10. ifican

    ifican Network Guru Member


    Thats always been my take as well though my coworker swears differently. I have challenged him to produce this documentation and he is still looking. Heck im even in support of leaving the write mem for a couple reasons, pix uses it (at least up to 6.x have not used 7 yet so cant say), but most importantly because i have used it for so long its just natural.

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