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Here's the setup: We have a corporate Time Capsule (or series of them, rather) with encrypted backups in the server closet. My Mac currently backs up to that. I've just completed encrypting an internal disk using TrueCrypt, and set it up using a .sh executable that launches at login. For the curious, it reads: /Applications/ --mount -v /dev/rdisk1s2 and rdisk1s2 is an internal disk on my mac, so as long as the password is correctly supplied, it should be available at all times. So far so good. When it mounts, it appears to the OS as though it were a .dmg.

And that's where things get hairy: I'd like to make sure my encrypted volume gets backed up to the Time Capsule. However, because Time Machine doesn't 'like' mounted disk images (apparently because it wants to preserve some vital assumptions regarding the availability of this disk...) it doesn't recognize the disk to back up.

So the question at this point is: How does one go about 'tricking' Time Machine into thinking the disk is back-up-able?

Thus the title: How does one go about referencing a mounted disk to make it appear to the OS as though it was internal?

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up vote 1 down vote accepted

It looks like you're not the only person with this question. As a workaround, could you use FileVault 2 for full-disk encryption instead? That does play well with Time Machine.

More information about why this doesn't work at Backup mounted drive of an image in Time Machine.

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Indeed my ultimate solution was to use diskutil cs convert /Volumes/WorkVault/ -passphrase XXX and forgo TrueCrypt entirely. With regards to the reasons that Time Machine won't work with my setup, the disk is not transient at all. It is internal and will be available as soon as the login script executes, so I really think Time Machine is just being clunky for this case. Even so, Time Machine is the best solution out there for well-integrated shadow backups. – zwerdlds Mar 6 '12 at 21:00

Normally, you can use hdiutil attach <image>.dmg to mount disk images. It will then appear to OS X as a normal drive, appearing in the Finder and rooted at /Volumes. Not quite sure whether that will work with a TrueCrypt volume though.

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The issue with this is that the partition isn't visible until I use the .sh I mention. And then, only the mounted drive is visible. – zwerdlds Mar 5 '12 at 21:13

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