bootable backup & two-way sync?

[pdxcarl]

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?

[dnanian]

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

[pdxcarl]

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.

[dnanian]

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...

[pdxcarl]

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.

[dnanian]

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...