How would TimeMachine work with two external (destination) drives?

Solution 1:

I haven't tried it, but since mountain lion, it just works.

Solution 2:

I don't think time machine will backup to two separate disks simultaneously, but I can give you my backup solution:

1. Time Machine to external drive. Easy and I don't ever have to think about it. Just plug it in and BOOM! backup.

2. Second, bootable backup to a second external drive using CarbonCopyCloner. This one runs on a schedule and it's a free program.

3. Dropbox. I have the 50gb account, and I store all of my current projects, important documents, and anything else i may need at any time, whether I'm in front of my Mac or not. Using the Dropbox iPhone and iPad apps along with the web interface, I can always get to important files when I need to.

4. Finally, I use Arq to backup a copy of my library folder to an Amazon S3 bucket. This one is a paid app, but worth it because I'm paranoid and it makes me feel comfortable that even if both of my backup drives fail, between the S3 Library backup and my documents on Dropbox, I can recover from a disaster quickly and with minimal hassle.

Solution 3:

You might consider 1 Time Machine disk and 1 disk that is using CrashPlan. The CrashPlan disk can be offsite too.