QRecall is looking like the backup system we need to replace Time Machine. My wife and I have MacBook Pros, and I just have a question about archives. We have no problem getting two licenses, but what are the pros and cons of the two of us having one archive, vs. 2? We both use the same 3TB, network connected hard drive to back up what will likely become, between us, about 2TB of data.

Tom,

It's great that you're looking at QRecall for your data integrity needs.

The biggest advantage of capturing multiple computers to a single archive is storage efficiency. Any common data you both back up (example: you both keep a copy of the same 100 GB of music/movies on your computers) will be consolidated into a single copy in the archive. A minor advantage is that regular maintenance can be relegated to one computer, usually the one with the fastest connection.

The downside to sharing a single archive is that only one computer can update the archive at a time, so regular capture operations have to be performed serially which might not be convenient. And as archive size grows, the speed of operations decreases as the complexity of duplicate data analysis increases exponentially with size. So a 2TB archive will be slower to use than two 1.2TB archives.

Honestly, since you're only talking 2 computers and I doubt you have huge amounts of duplicate data between you, I would suggest starting with two archives and seeing how it goes. If you start to bump up against the storage limits of your device you can revisit this arrangement.

Postscript

One more thing: if you really want to see what the effect of using two identity keys are, get two trail keys from the website. Use them to create individual archives for each computer, then create a single archive and capture both computer to that. It may take a couple of days to test these out (four full, first-time, captures over a networked storage device), but it will definitively show how much storage savings you'll get.