sparse images, sparse bundle images, and encryption

[nephdoc]

Last weekend, I lost a hard drive that contained two things:

1. my SuperDuper automated backup of my boot volume
   
2. a separate partition containing a password protected and encrypted sparse bundle image volume that I use for storing confidential stuff (HIPAA compliance issues on my laptop one reason for doing this).

In recovering from this, I've done some reading about sparse images and sparse bundle images that I should have done much earlier, prompting some questions about how they're handled by SuperDuper:

If a sparse bundle image is encrypted, does the encryption make it impossible for SuperDuper to back it up incrementally and restore it incrementally; i.e., do the 8 MB "stripes" get hidden or changed by the encryption in such a way that the sparse bundle loses its value as opposed to a simpler sparse image?

Just where is the password for a sparse image or encrypted sparse bundle image stored? In my keychain? In the image itself? I'm wondering what happens if I need to restore an encrypted sparse image to a new destination.

Lastly, does the password protection prevent or hinder SuperDuper backing up a sparse bundle image?

Thanks so much,

Jim Robertson

[dnanian]

The encryption is at a lower level, so there's no problem backing up the separate band files inside the bundle. Note, though, that the volume should not be mounted when you back it up.

The password for the bundle/image is in the image/bundle itself, unless you explicitly also add it to your keychain.

[nephdoc]

Originally Posted by dnanian

The encryption is at a lower level, so there's no problem backing up the separate band files inside the bundle. Note, though, that the volume should not be mounted when you back it up.

The password for the bundle/image is in the image/bundle itself, unless you explicitly also add it to your keychain.

Your warning prompted me to revisit information about Time Machine and FileVault. Apparently, Time Machine won't work with FileVault unless you're logged out of your user account (Time Machine skips backing up the Home Folder) which makes sense in terms of not screwing up the encryption. I've never used FileVault, and I'm wondering now what Time Machine displays in its "Time Travel" interface for the Home Folder. Can it "see" individual changed files that it's backed up previously while the user was logged out, or does restoring require restoring the entire home folder?

I know this isn't a Time Machine Forum, but I'm just trying to understand the capabilities of the individual backup and restore solutions.

Thanks again for your prompt response to my original question!

Jim Robertson

[dnanian]

I don't know what Time Machine does with FileVault: I don't use FileVault.

Note that SuperDuper! also needs you to log out of a FileVault account before you back up its host drive. We can, of course, back up the mounted FileVault volume itself (it appears in the source pop-up), but that's a different thing entirely.