SD and Retrospect together?
 

Question briefly stated: Can I run Retrospect in a Sandbox so that I can have archival backup of the user files on my G5 as well as archiving the user files from my wife and children's laptops over my home LAN?

To elaborate: After reading Joe Kissel's excellent Mac OS X Backups from the Take Control eBook series I established a backup system for my family using Retrospect as a server on my G5 and as a client on their laptops. It allows me to make nightly regular scheduled archives of all of our User folders to external FireWire HDs attached to the G5. The G5 and the laptops also make weekly sequential duplicates onto boot-able FireWire HDs (attached to the G5 always and attached to the laptops intermittently but regularly). So far so good. But as you know though Retrospect can make fine duplicates it is somewhat time consuming to restore from such a duplicate if some rogue update causes a system to become unusable. Super-Duper! looks better at making duplicates in general but in particular the idea of applying updates first in the Sandbox without affecting the definitive source system seems like it would be significant improvement to my current system. Particularly since my G5 has 2 Internal HDs it sounds like recovery could be quite quick and painless. Also updates wouldn't be be so anxiety provoking. I know that Super-Duper! backup strategies are based on the premise of using several sequential duplicates instead of an archive but in this case I have a working archiving system of several machines over a network and would like to just add the Sandbox recovery capability to what I've got; first on the G5 because of the 2 internal HDs and possibly later on the laptops depending on whether their drives are large enough to accommodate a Sandbox volume.

Would Retrospect running in the Sandbox on one of the G5's internal HDs properly "see" the User files on the original copy of the system residing on the other internal HD? Would symlinks of the files fool Retrospect into using the original files? This sounds like magic too good to be true, or at least too complicated to be utterly trustworthy. On the other hand, based only on my shallow understanding of what's actually going on I don't think there would be any problem with the client archives.

A related question: When does more redundancy decrease reliability by increasing complexity?

Thank-you to anyone who makes it this far.

PS
all machines are PPC/10.4.8/with updated Retrospect Desktop and SuperDuper!

The key to the backup is to continue to back up the original drive, not the Sandbox. There's no need to back up the Sandbox.

As long as you do that, Retrospect should work just fine in a Sandbox configuration.

I don't think Redundancy does decrease reliability, except in the sense that having too many FireWire or USB devices can decrease the reliability of OSX itself.

Thank-you Dave
 

Thank-you, that sounds great.

How does having too many external devices decrease the reliability of OSX. How many is too many?

FireWire itself can get less stable as you complicate the bus with many devices. It all depends on how well implemented each device is, how many require power, etc -- you'll know when you're having trouble!