Caring for your Dynamips install – deleting unwanted files

Dynamips and dynagen are well behaved programs most of the time. Occasionally I am configuring a feature or two that causes IOS to crash (most recently I was configuring MPLS and redistribution on c2600 IOS which got really busted).

Then I noticed that my hard drive didn’t have a lot of free space….

I have a MacBook Pro with a 160Gb drive, and I need to be careful about available space. I looked into the my Dynalab directory (why ?and found a number of files that can be deleted. As you can see in the screenshot, I have a log file that is over 1 Gigabyte in size for R8, and the dynamips log file is 250MB


Since these are log files they can be deleted, as the log files are locked by dynamips make sure it is not running.

The log file is due to the IOS crash I had. I no longer use any other images but the C3640 image. I think that this uses less memory because of the memory shadowing features implemented in dynamips. As I understand it, when you use the ghostios==true, dynamips loads a single copy of the IOS image into RAM and then all of the routers you use will reference that single copy of the file.

About Greg Ferro

Greg Ferro is a Network Engineer/Architect, mostly focussed on Data Centre, Security Infrastructure, and recently Virtualization. He has over 20 years in IT, in wide range of employers working as a freelance consultant including Finance, Service Providers and Online Companies. He is CCIE#6920 and has a few ideas about the world, but not enough to really count.

He is a host on the Packet Pushers Podcast, blogger at and on Twitter @etherealmind and Google Plus

You can contact Greg via the site contact page.

  • Nizar

    Can you ask Greg if he knows how to configure Olive (“Dynamips” for Juniper)?

    • Greg Ferro

      I don’t know about olive so I can’t help. Sorry about that.

  • ccie25655

    Also note that you can simply send log files to /dev/null when you start up your dynamips instance.

    @Nizar: You can read an olive tutorial here:

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