Disk images

Use disk images

As described in Install a specific disk image on a node you can use varying images and OSes for your nodes. We provide standard images, but you can also create your own.

Create your own disk image

You can use e.g. the jFed tool to create a new image as follows. Suppose you have set up an experiment and installed some software, and want to create an image of a specific node.

In jFed you right click the node, and chose Create image. You will see the dialog box to chose an image name:

_images/diskimage1.PNG

Chose a name for your image, and you will see the next pop-up informing you how to use this image in a new experiment:

_images/diskimage2.PNG

Now, the testbed will reboot your node and take an image (which may take about 10 minutes). You receive an email when the image is ready (containing also the above unique IDs).

If you use jFed, in your new experiment, you just put the image URL (works on all virtual wall, instageni, emulab testbeds, the image is fetched automatically from another testbed if needed) or image URN (only the same testbed where you created your image) in the image field when configuring a node:

_images/diskimage3.PNG

Caveat: system users

There is a caveat when you install software which creates system users (e.g. mysql or postgres user, etc). The testbed refreshes the passwd file when installing a new node, so your users will be overwritten.

To prevent this, do the following on your node prior to taking an image:

sudo su
/usr/testbed/lib/prepare -M

Caveat: new OS

The above starts always from an existing image (containing the testbed tools already). If you would however need a new operating system image not yet listed, then contact the testbed admins to discuss (vwall-ops@atlantis.ugent.be).

Anyway, this procedure is documented here: Creating emulab image from scratch. (this is not trivial)

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