Mac and Backup newbie, sizing sandbox and sparce image

[dnanian]

Sharing applications doesn't make them slower, since it just links to the original application, on the original drive.

The easiest way of determining the size of a Sandbox is to create one on a blank partition, before you partition for real. Check the size, give it at least 20% slack plus space to grow. We usually recommend 8-12GB or so.

If you're going to use a Sparse Image, we size it automatically, with its maximum being the size of the drive.

You're right w/Sandbox updating the original. Just follow the steps in the User's Guide.

Finally, remember that user files on the Sandbox are really on the original drive, so deleting files when booted from the Sandbox are really deleting them from the original. Also, remember that there's no need to back up the Sandbox; always back up the original volume.