Currently Being ModeratedJan 24, 2013 2:45 PM (in response to Linc Davis)
Good point - I do not use virtualization software - but I do have several disk images that get modified daily and are encrypted, so I suppose the end result is just like the virtual-disk container case you suggested. They do add up to roughly the data size in question.
Currently Being ModeratedJan 24, 2013 3:29 PM (in response to mandrake.l)
Then you should be aware of a couple of points. First, Time Machine will not back up a disk image file while it's mounted. Make sure you unmount the image frequently so it can be backed up. If you ever restore, you will, of course, lose all changes made since the last backup.
Second, there are different kinds of disk images. The best kind to use for a read/write volume is a "sparsebundle," which is not a single file but a folder containing many small, hidden files. Most of those files won't change between snapshots, so backup will be more space-efficient than with an older type of disk image.