[Ledgem]

Originally Posted by Irenicus

[*]Which is better and/or cheaper, an external HD or an internal HD + external closure?

I have tons of externals, and my preference is always to go for an external enclosure with an internal hard drive loaded in. The up-front cost is almost always more expensive than buying an "external hard drive" but there's more versatility. I've also experienced a scenario with a failing enclosure twice, once with an enclosure + internal HDD and once with an "external hard drive." I still had my drive when I sent the enclosure back for a new one, but with the "external hard drive" I had to send the entire thing back and received a "new" (refurbished) enclosure+drive.

That said, I'm leaning more toward "external hard drives" these days. As of now I have six enclosures hooked up to my computer. In theory one of the benefits of the enclosure is that you can just swap out the hard drive inside of it with a newer one, but in practice I haven't had any HDD failures yet (super lucky, including one PATA drive from 2001/2002) and instead of discarding a lower-capacity drive with a larger one I just keep buying new drives and enclosures to put them in. Basically, I'm probably spending more and yet I'm not utilizing the strengths of such a setup in practice. (Sure, my hard drives and enclosures are probably higher-quality than what you would find with an "external hard drive" but I don't imagine this makes a huge difference.)

Long story short, "external hard drives" still make me nervous, but in practice they're probably fine and make more sense financially.

Originally Posted by Irenicus

[*]My current system and formerly just storage drive is 1.5 TB, but it's like 1/3 if not 1/4 full. Do I need an equivalent sized drive to backup? Can 1TB do? 2TB?

This partly depends on your backup solution and backup expectations. If you just want a 1:1 "mirror" of sorts then your backup drive only needs to be as large as the amount of data that you have. A 1.5 TB drive that never has more than 500 GB on it could be perfectly served by a 500 GB drive, for example, although going with a drive of the same capacity would be the safest.

One benefit of certain backup solutions is incremental backups. It's not just a 1:1 mirror, but contains copies of the history of the file. The usefulness of this is being able to go back to recover a version of the file before you edited it in a certain way, or if the file became corrupt some time ago but you didn't realize it until recently. In that case, the larger the drive, the more "history" it can save.

Originally Posted by Irenicus

[*]What are your data habits?

OS X's "Time Machine" with certain important files (photo library, family videos) mirrored across multiple drives manually. I thought that Microsoft had implemented a Time Machine-like service in Windows; if not, there's probably a third-party solution that you could utilize. (Actually, according to the first answer to this question, Microsoft has a pretty neat backup solution in Windows versions Vista and 7.)