bootable backup & two-way sync?
 

What I want to accomplish:
1. Create a bootable backup to an external firewire drive on my personal Macbook Pro (Computer 1).
2. Take external firewire drive to work, plug it in to my Mac Mini (Computer 2), boot from it and use it all day. Applications, settings and files will obviously get changed, deleted and added throughout the day.
3. Take external firewire drive back home every evening, plug it into Computer 1 (but not boot off of it), and synchronize all changes with the internal hard drive.
4. Rinse & repeat.

My reasoning is that I don't want to carry my laptop to work every day and I want to minimize the wear and tear of my own personal laptop when I already have a perfectly good computer at work. However, I sometimes work from home and want to make sure that all files exist on both the internal and external drives.

Does anyone know how to accomplish this?

Rather than use a bootable volume for this, why not just store the files you're working with on the external drive?

That would be a great solution if it were only data files I want to have available. However, because I also want to have all my software available, and specifically because I don't want to have to go through the headache of installing software, deleting software, updating software, trying to remember to match the settings, preferences, etc, etc on two different systems, perhaps that will provide some insight as to why a "data only" storage solution on the external drive doesn't work for me.

What I want is my computer, configured my way on an easy to carry external hard drive. Software exists to sync the two drives both ways (Synchronize! Pro X, Synk Professional, ChronoSync, etc), but I don't know how to get it to "play nice" with my bootable backup configuration. I suspect that whatever solution I come up with will have to be a hybrid solution, wherein I select only the directories (Applications, Home (User) directory, and whatever else might get changed throughout the day, including preference files, permissions, etc, etc), but I'm not sure what to sync (and what to leave out) and how to go about it in a way that will maintain bootability and not mess anything else up.

The net result should be that whatever is on the external should exist on the internal (and vice versa). This accomplishes my goal of portability and an up to date backup of my system.

Understood. While I think you could probably jury-rig something like this with SD, I don't think it's going to work well, and will likely be error-prone...

I would have thought this might be easy since I only want to boot off the external drive on the second computer instead of trying to sync that computer's internal hard drive with the external drive. Basically, all I want to use the second computer for is it's CPU, RAM, keyboard, mouse and display adapter.

I've spent hours searching for a solution. What's most surprising to me is that no one else seems to be searching for an answer to this but me. I would think there would be plenty of people who are in a similar situation. I hope someone is able to jump in and help me figure out a way to accomplish this.

It's not that it's not relatively easy. You can do it as long as you're willing to start up from the external drive before you "sync back" to the original computer. But we don't do "two way" sync, so you have to make sure you don't use the other computer before you re-sync... and, as I said, this sounds like a situation where it'll be easy to be tired and make a mistake...

There is away... Sort of
 

Create a clone of your "Home System" Boot off your Clone at home for day to day use. Bring your clone to work and boot of it there.

You have to remember to Keep your Clone backed up and perioidcally restore your clone to your home computer for when you wish to go mobile with your Macbook instead of your drive, in which case you would reverese the process.

Note that this only works with campatible booting systems.

pdxcarl

athlover has basically provided your solution. I have worked with your exact situation for a number of years. We know both your computers will boot off the system cloned on the backup, since it is a clone of Mac1 and you say you take it to work and boot Mac2.

Why not just change one thing in your proposal: boot the home machine as athlover suggests off the same external drive? I don't understand's any difficulty about needing to sync, update, re-clone, ect. You have SuperDuper. In effect, your portable becomes your computer and your only boot drive. This is what I do, and if the portable is large enough (mine is large) I find I only use the work computer's internal for storage, really, and at home pretty much ditto.

The portable must obviously be backed up with SD religiously; for this another disk can be used, or the internal of either work or home Mac (or both) can have a SD backup partition on it OR be an exact clone of the portable. You may also have some huge archives at home which you really don't need at work, or to haul back and forth (graphics files, iTunes library, etc.) but these almost never need to run from a boot volume, and most have preferences which will allow any additions to be pointed at the library volume. Obviously, you would then need to back up these archives as well.

As long as both machines will boot from the same OS disk, this to me is by far the most elegant and simple solution. It has served me well for over six years of work now, and the glory of never having to worry about syncing and what is where far outweighs the problem of backing up archives. (On the home machine, I have a 500g internal archive disk and another 500g internal to back it up, via SD of course, which I only normally do every 7 to ten days, since it seldom changes much. And yes, a 500g mirrored array would accomplish pretty much the same thing.)

Since your home computer is a laptop, you might need a firewire hub and another external to make this work, but both are getting pretty cheap.