possible to make bootable disk with external HD?

[ghostmeat]

This might be a dumb question but I'm not so well-versed with hardware issues.

I know how to make bootable DVDs and USBs for reinstalling OS on my MBP (I'm trying Lion in particular) and was wondering if it would be possible to use an external HD for the same thing. I have no DVDs or USBs with enough gb for the install, but I have a 350gb HD which I use for all of my movies/tv shows. If I make a bootable disk with the HD, will it be able to return to its original format after?

Again, this might be a really stupid question, I just can't take any chances with my external.

 

[Freyqq]

To the computer, an external USB hd is basically just a really big USB flash drive. There is no difference. If you computer supports booting off USB, then it will work fine. However, to make it bootable, you might have to reformat the drive...or at least give it a new bootable partition.

 

[blueroom]

This might be a dumb question but I'm not so well-versed with hardware issues.

I know how to make bootable DVDs and USBs for reinstalling OS on my MBP (I'm trying Lion in particular) and was wondering if it would be possible to use an external HD for the same thing. I have no DVDs or USBs with enough gb for the install, but I have a 350gb HD which I use for all of my movies/tv shows. If I make a bootable disk with the HD, will it be able to return to its original format after?

Again, this might be a really stupid question, I just can't take any chances with my external.

1. Always have a backup solution. Eventually you will lose a drive.
2. You'll need at least a 8GB USB whatever to install a bootable OSX installer image on, you will need to format it as HFS+ and that'll most likely kill anything on it.
3. There are tools for creating OSX install USB boot doodads, Google USB Lion installer.
4. Storage is cheap.