Sparse image from aborted DMG backup?

[Winston]

I tried to back up a drive containing about 7 GB to a drive that had about 12.5 GB free. To make the final DMG disk image SD! first makes a sparse image, then makes a DMG image from the sparse image. There are two backup images until SD! finishes - taking up twice the disk space.

Most of the way into the backup I realized that SD! would not have enough room to finish. Setting the backup to maximum compression did not help enough.

I stopped the backup and trashed the incomplete DMG image. I opened the sparse image that was left. I had what looks like a complete backup.

1. Is the sparse image a complete backup?

2. Can I use the sparse image for incremental backups as described in the FAQ for creating a "modifiable" disk image?

3. Can SD! warn about backups that won't work because there is not enough disk space?

4. Copying from the sparse image to the DMG image is slow. If the sparse image and the DMG image could be created on separate drives the copying would be a lot faster. Is there a way to do this? If the sparse image is made on the original drive then making it will be really slow, and you don't want the DMG image on the original drive. Would a third drive allow a disk image backup to be faster?


- Winston