Keep user’s home folders separated from the system so a re-image will not destroy their data.

Requirements For This Walkthrough

Downloads

1. Users Icon

Resources

• http://macmule.com/2012/07/31/how-to-use-fstab-within-a-casper-imaging-workflow/
• https://github.com/ox-it/mac-scripts
• 2013 JNUC: The College Challenge Macs at Oxford

Why Do This?

Re-imaging a computer is often the fastest recovery method, but it is destructive because it erases everything.  Mounting the /Users  folder on a separate partition allows you to re-image a computer without destroying the user data.  This allows you to deploy the System partition without worrying about user settings.

Likewise, end-users can set things the way they want.  They can even keep their own ~/Applications  folder.  This separation or User and System integrates well with Apple’s methodology of resource domains.

Caveats

• Increased complexity because two partitions need to be managed
• Users may run out of space based on what sizes were chosen for the partition
• The System partition may run out of space based on what sizes were chosen for the partition

How-to

Inspiration

Marko Jung presented The College Challenge at the 2012 JNUC (and the similar presentation The Egg of Columbus in 2013).  I loved the concept but was not versed in Perl (language used for partitioning the disk), so I decided to try to make a bash version of the workflow.  It is not nearly as advanced and does not have a lot of error-checking, but I plan to improve this over time.

Conceptual Overview

1. Erase/partition the disk with a bash script
2. Deploy an /etc/fstab  file at imaging time
3. Modify /etc/fstab  on the first boot after imaging with another bash script
4. Change the icon to look like the normal /Users  folder so end-users don’t really know anything is different

Step-by-step

Create the partition-disk.sh  Script

Below is the script to run before deploying the image.  It will partition the disk into three partitions: Macintosh HD, Users HD, and Recovery HD.  Adjust the disk sizes per your environment.

Create /etc/fstab

Using Casper Composer, capture a new package to capture the /etc/fstab  file as well as the /Users  folder icon, which will both be deployed at imaging time.  Use vifs  to edit /etc/fstab  with the following line:

LABEL=Users\040HD /Users hfs rw

This will mount the /Users  folder to a partition named exactly Users HD using HFS+ and making it read/write.  This file needs to be deployed before the image is applied.

Install the New /Users Icon

For the second part of the package, create a new folder to store the icon: /usr/local/imaging/users.icns.  Copy the icon into this folder.  This will be applied to the /Users  partition on first boot so that it looks like a regular folder. The icon I created just uses the normal icon with a little disk-slice badge on the bottom right.  From a distance, this looks like a normal folder to an end-user, but an admin will easily notice the badge, which will be an indicator that the workflow worked properly.

Create the package with Composer and save it as a .pkg.

Create A Script to Modify /etc/fstab

This script will tell the system to mount /Users  to the UUID of the Users HD partition.

Create A Script to Change the /Users Icon

This script will copy the icon deployed from the previous .pkg to the root of the /Users  partition.  This command works because it is a Volume and not a folder.  If it was just a folder, the process to change the icon is different.

Create the Workflow

This is what the Casper Imaging workflow looks like without any additional packages.