So I get an external HD for the purpose of doing Time Machine backups of my MacBook Air (running Lion). When setting up Time Machine it asks if I want to encrypt the drive, which sounds like a good idea. As I understand it, if someone got possession of the HD without encryption they would simply need to plug it in to access then data. Its a portable and its going with me to uni, so I checked the option to encrypt. Here's the thing, I've been doing encrypted backups for a couple of days now and each backup seems to take forever. Even when not much has changed, doing a backup takes a significant amount of time. Of course i'm willing for the backups to take longer if it means better security, however my Air is NOT encrypted which got me thinking about if I really need to encrypt my backups. Am I right in thinking that it would be easy to access all the files on my MacBook Air even if you didn't have the lock screen password, for example starting it up in target disk mode and reading the files from it? If this is the case then having backups encrypted seems pointless. I don't store any sensitive data, and while I wouldn't want anyone to have access to my work and files, it would probably all be useless to anyone else. I've read other reasons not to encrypt your backups and it seems like its a bad idea, at least for me. So should I use encryption or not? I'd be interested to hear any good for and against arguments.