Disk Image versus volume root?

[pirkka]

Hey, I use SuperDuper! to back up my MacBook's internal 74GB hard drive to a LaCie 233GB external disk.

By default, the backup takes up the whole LaCie volume, leaving ~150 GB of unused space on the external volume.

Fortunately, I realised that I can also back up to a Disk Image file on the LaCie, so that the rest of the volume can be spent for storing files that don't currently have on my MacBook's internal drive.

Now, my question is: how robust/error prone is the Disk Image format? I'm stuffing a million files into a single Disk Image, and I just can't help but to wonder if some kind of file corruption occurs in the Disk Image on my external back up drive, is it all lost forever? When backing up to the volume root instead of Disk Image, I can see all the files there as separate entities - if one of them gets corrupted, I figure that the rest will still work fine.

[dnanian]

That's right. Disk Images are something to be used when you can't write directly to the volume for some reason. In general, if you want to store other files on the drive, the thing to do is partition the volume, rather than use Disk Images. But, if you're stuck and can't, then a Disk Image is generally reliable. It's just another level of indirection that's best avoided if possible.

[pirkka]

Oh, PARTITIONING! *doh* How did I not think of this myself.

Thanks a bunch... I'll look into partitioning my LaCie!

[dnanian]

Make sure to use the right partition scheme for your Mac type (click the "Options" button in the Partition tab).