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I need some answers, pronto.

1)If i get an external hard drive that says 2.5", does it mean the thing inside, or the case with it?
2)Do internal hard drives work as an external as long as you put it in a case, and vice versa?
3)When you get a hard drive thats 320gb for instance, the actual space is actually something around _____. Is there like a sort of mathematical rule to this? like 1/10 of the space cant be used?

Yeah thats it, hopefully somebody knows the answers :)

1) That would refer to the overall dimensions of the drive.
2) Nope.*
3) That's generally due to the difference between decimal units and binary units. In decimal SI terms, a kilobyte is 1000 bytes, whereas in binary units a kilobyte is 1024 (2^10) bytes. Manufacturers talk in decimal terms (which look larger) while the computer uses the binary definition. The difference between the two gets bigger as the size you're referring to increases—for example, 100 decimal megabytes is around 93 binary megabytes.

* Edit: actually, maybe they could. You can get USB adapters for internal hard drives, but you'd still need a properly shielded case. I revise my answer to "not easily".

So externals can still be internals?

z3phyr wrote:So externals can still be internals?

No. I mean, you could mount one inside your computer case if you were enterprising but it's not going to function like your standard internal hard drive. External drives connect in different ways (e.g. USB) to internals (e.g. SATA).

An internal drive can become an external drive for sure. Look up 'drive enclosure' and you'll find empty cases you can insert a standard hard drive into and then transfer data over the case's USB (or firewire or whatever) port.

I've never thought about taking the drive out of an external drive and making it external. They're probably just the same kind of drive you can get anywhere, but I wouldn't count on it without knowing first. The data and power connections could be soldered in place, for example, to make sure the drive never came loose. So internal to external, yes; external to internal, maybe not.

z3phyr wrote:I need some answers, pronto.

1)If i get an external hard drive that says 2.5", does it mean the thing inside, or the case with it?
2)Do internal hard drives work as an external as long as you put it in a case, and vice versa?
3)When you get a hard drive thats 320gb for instance, the actual space is actually something around _____. Is there like a sort of mathematical rule to this? like 1/10 of the space cant be used?

1) Depends on how the manufacturer listed the specs, if it just says '2.5"', that doesn't really list dimensions, therefore I would assume that means it has a standard 2.5" HD inside of it. (Link to the specific drive and I could probably tell you)
2) -what LV said- plus, some manufacturers literally put internal drives in plastic cases and sell them as external, so it would be possible to remove them and put them inside, once again, depends on the manufacturer
3) There is no definite rule per say, but to get a (really) rough estimate, just guess it at 95% usability of what it says it is (my 500gb comes out to 465 after formatting, which is roughly 93%, and my 640 comes out to right about 600gb usable, which is around 94%)

That's because HD manufacturers use 1kb=1000 bytes instead of the actual 1024 as a marketing scheme. Aslo, if looking at internal drives, how old is your PC? If it is 4 years or older, it may NOT have SATA ports and you may need an IDE (nowadays called PATA) drive.

So you can turn a regular hard drive into an external one, but can you do it the other way around?

maestro wrote:So you can turn a regular hard drive into an external one, but can you do it the other way around?

You can do it both ways. External hard discs are just internal hard discs (although sometimes with fancy features not common on internals like shock protection) in an enclosure that provides shielding, shock mounting, and a USB/FireWire/eSATA/whatever interface. This comes with the caveat that external hard disc enclosures are sometimes very difficult to open (I'm looking at you, LaCie). You can quite easily obtain hard disc enclosures for using a standard internal drive as an external drive. These can be as cheap as $20, but you get what you pay for. In general they'll all work fine for moving files on and off of the drive, but you'll see varying access speeds, interface options, and drive protection depending on how much you pay for the case.

Note that you should use caution when putting very large (750GB and up) or fast (10'000 RPM) drives in external enclosures, as external enclosures not designed for such drives will rarely provide sufficient cooling, which may result in premature failure. Also remember that opening a manufactured external drive to remove the internal HDD will, of course, void the warranty.

Keep your interfaces in mind. Most external HDDs use IDE (PATA) internally (between the drive and the enclosure), whereas SATA is becoming more popular in computers. so if you plan to swap drives between the two, check to make sure the interface types match up.

External interfaces for external drives (between the enclosure and the computer) may also be an issue. Your three main contenders are USB2.0, Firewire 400/800, and eSATA.

In order of speed:
USB1.0
USB1.1
Firewire 400
USB2.0
Firewire 800
eSATA
USB3.0 (not released yet, but should start appearing on the market within the next couple of years)

USB2.0 is probably your best choice, as virtually all computers have USB2.0 connectors. FireWire 800 is a faster option, but is not as common on computers (and beware of the Firewire 400/800 distinction - Firewire 400 is much more common than 800, but is actually slower than USB2.0). eSATA is not terribly common but is very fast. if you get an eSATA external drive, plan on buying a PCI (for desktops) or ExpressCard (for laptopts) eSATA controller.

That is all.

I'm putting this in my ps3