escape :: system imaging

by Brian Reichow
November 13, 2006

Not too long ago, setting up a new Mac from scratch or reinstalling the contents of an existing Mac took several hours (installing system software, applications, updates to each, printer drivers, creating accounts, setting all common preferences) -- even longer if it was necessary to copy existing user data off (and then back on) post-reinstall.

Since each machine was set up at a different time and sometimes by different people following different processes, each machine invariably ends up slightly different. This inconsistency between machines makes diagnosing issues more difficult.

By standardizing on an identical setup for each Mac, one can reduce setup and re-setup time from several hours down to as little as 15 minutes. This process is known as system imaging. An "image" is a file containing an exact duplicate of the master machine's hard drive. The "image" can be duplicated onto other machines via the network or an external hard drive by using system imaging tools, completely replacing the contents of the Mac's hard drive.

Imaging makes the "best practice" of change management (or change control) a snap. One test machine with new or updated software can be placed into an existing workflow as a guinea pig, and based on the user experience with that one machine, the master "image" can be refined and bugs worked out before it is deployed wholesale on the rest of the machines. One can expect consistent user experiences on all machines when this practice is followed.

Worst case, one can go "back in time" to an earlier image should a serious problem manage to sneak through the testing process.

Imaging makes certain things practical, including highly customized environments, simply because the tedious hands-on work only has to be done once. Combined with Apple Remote Desktop, it reduces the need to physically visit each machine, too.

Also, rather than spending large amounts of time diagnosing any issues that crop up down the line, it's often quicker (and therefore less expensive) to simply re-image the machine to the known-good "master" state. If you have in-house junior IT staff with minimal Mac diagnosis skills, a simple re-imaging can avoid the need for advanced diagnosis entirely unless the machine continues to exhibit the original problem. It's quite a change from the old-school repair mindset, where avoiding a "nuke and pave" was paramount due to the time involved. Not so anymore!

With today's system imaging tools, it is even possible to "multicast" an image to dozens or even hundreds of machines at once, reducing the time required to reimage machines even further than traditional imaging.

We have education customers who completely re-image computer labs within a single class period. This allows a lab to be used for many, many different purposes even if the hard drive is not necessarily large enough to accommodate the software required by all possible purposes at once, or simply so only the software required by that particular class is even present on the computer.

Also, since machines inevitably get messed up or otherwise abused through general use by students, reimaging allows them to be quickly restored to service by returning them to the preferred, clean, "master" state.