December 8, 2010 My Mac First Aid Kit


I nuke and pave my home computer every two or three months, but at work it seems like I am performing the same process on someone else’s Mac at least once a week. Having all of my software tools together on a single external hard drive not only makes my nuke and pave process go faster, but also reduces the amount of equipment I need to troubleshoot a Mac. My Mac First Aid Kit allows me to boot my patient from a known good installation disk, diagnose the ailment as hardware or software, backup any valuable data, and restore the OS, user data, and applications from a single external hard drive. This is how I setup and deploy my Mac First Aid Kit.

Picking a Drive

A Mac First Aid consists of a single external hard drive with a minimal set of requirements.

Portability is most important. There is no point in building a Mac First Aid kit you cannot easily bring to your patient unless of course you are in a business where your patient comes to you. (Apple Store Mac Genius for instance) I’d look for a 2.5 inch external hard drive that is bus powered. The last thing I want to do is lug around a power supply the size of an equally capable external hard drive. USB flash drives are also an option, but most do not have the required capacity or connections to do the job.

Capacity is not as important as you might think, but my external hard drive should at least be large enough to back up my patient’s data with room to spare. I aim for the 500GB – 1TB range. Any larger and most users use external disks to hold their important data. Any smaller and I might not have enough room to backup everything.

Interfaces are my First Aid Kit’s bedside manner. They are the only means of making a connection with my patient. In today’s era of Macs without FireWire USB is a requirement, but I occasionally still visit older PowerPC Macs that can’t boot from USB. I recommend a drive that has at least USB 2.0 and FireWire, with both the 400 and 800 varieties being a plus.

When it comes to my Mac First Aid Kit I chose a LaCie Rugged 500GB triple interface drive because it meets all of the requirements above and comes in a rugged swappable rubberized shell that protects my drive between house calls.

The Setup

Disk Utility is always my first destination after unpacking any new hard drive. I never trust the filesystem on a new drive until I have formatted it myself. Every virgin hard drive is a potential life raft for malicious software, hidden partitions, and cosmetic filesystems. It is best to flatten the whole thing than risk any of these ailments on a potential patient. And besides when did an external hard drive ever come with valuable software anyway?

I start by selecting my new hard drive in Disk Utility’s source pane, choosing the partition tab, and selecting a minimum of four partitions.

The first two partitions I name Leopard, and Snow Leopard, and make each 8GBs in size. If I was still supporting Tiger or Mac OS 9 I would make additional partitions for these operating systems as well.

The third partition I name Software. Its size is dependent on the size of the software I usually need to install on any given machine. I made my Software partition 60GBs, but with the help of Disk Utility’s live partition resizing it’s always possible to resize it again later.

My Mac First Aid Kit’s forth partition is reserved for archived user data and takes up the remaining space on my hard drive. Later on this partition will be filled with temporary Time Machine backups or clones of my patient’s hard drives.

After naming all of my partitions and adjusting their capacities it is important I select the Apple Partition Map before clicking apply if I plan on booting PowerPC patients. It is a little known secret that hard drives partitioned using the older APM scheme required to boot PowerPC Macs can still boot newer Intel Machines that normally require GUID. The catch comes from the fact that Mac OS X cannot be installed on an APM drive when booted from an Intel Mac, but this is a limitation I easily overcome using the following technique.

With my four partitions in place it is now time to start populating my Mac First Aid Kit with useful software. I begin by inserting my retail Leopard installation CD, and dragging the Leopard CD icon from the left of the Disk Utility window into the Source field of the Restore tab. I then drag the first partition of my Mac First Aid Kit into the Destination Field. Before clicking the restore button it is important I check the Erase destination option in order to make the resulting restore a fast block level copy.

I repeat the restore process using a retail Snow Leopard Installation CD for the second partition of my Mac First Aid Kit.

In order to be an effective platform for rebuilding machines my Mac First Aid Kit must include a copy of all the software I regularly install on a patient’s hard drive. For software available on the internet this process is as easy as downloading the required application installation files and placing them in my Mac First Aid Kit’s Software partition. For physical media such as CDs I must select the installation disc from the left of the Disk Utility window and choose the File > New > Disk Image from¬Ö command from the menubar. I will then save the disk image as a DVD/CD master and place it in my Mac First Aid Kit’s Software partition.

In Use

After my external hard drive has been selected, partitioned, and bestowed with software it is time to put my Mac First Aid Kit to the test. The basic scenario goes like this.

Mac Z freezes when application Y performs task X. After reinstalling the faulty application, repairing permissions, deleting preference, and performing the same task under a new user account a solution to the problem can not be found.

Before proceeding further to more destructive troubleshooting techniques a backup of the existing environment must be made. If task X is not affecting overall system stability, and Mac Z is running Mac OS 10.5 or later I proceed by committing a full Time Machine Backup to the Backup partition of my Mac First Aid Kit.

Time Machine is my first choice in backups because it can be resumed if the process is prematurely halted, and because it can exclude parts of the filesystem not requiring a backup. If Mac Z is running 10.4 or older I would boot from my Mac First Aid Kit and clone Mac Z’s hard disk to my Backup partition using Disk Utility and the very same process I used to copy my installation media.

Normally the next step to diagnosing the problem would be booting from a known good installation of Mac OS X and attempting the same task with application Y. Unfortunately the only known good installation of an operating system is the one installed on the same hardware or a compatible installation disk supplied by Apple. Booting from the compatible installation media on my Mac First Aid Kit is one way of determining if Mac Z’s hardware or software is at fault.

Restarting while holding down the Option key allows me to boot from one of my Mac First Aid Kit’s installation partitions, and the built-in terminal application allows me to stress test Mac Z. Commands such as yes > /dev/null will quickly max out the CPU, while find /Volumes/Macintosh HD will exercise the hard drive’s ability to list a complete file manifest. If it is a graphics issue I am after rapidly moving around the terminal window while conducting these commands might just reproduce the issue. If at any time I am able to reproduce the problem while booted from an external drive I have determined the issue is probably not software related and requires a hardware repair. If I am still not able to reproduce the issue in this manner it is time for a Nuke n Pave.

As you may know I don’t believe in the Upgrade, or the Archive and Install. If I am going to do something I might as well do it right and rebuild Mac Z from scratch by formatting the drive, reinstalling Mac OS X, and restoring from backup.

After the installation process is complete and Mac Z has rebooted it is time to restore the user data and applications from my previously conducted Time Machine Backup or system clone using the Migration Assistant. If only a certain application is causing the problem I may not restore all of Mac Z’s previously installed applications immediately, but work my way up installing each possible problem app one at a time from my Mac First Aid Kit’s Software partition. Hopefully at this point I am unable to reproduce the problem, and can chock the solution up to a clean operating system, and freshly installed applications.