External Storage Solutions - Cheaper USB Hard Disk Drives

External HDDs and their components

I recently had a quick foray into the world of external hard drives. A hard disk drive (hard disk, hard drive, or HDD) is a non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. [Wikipedia :)] I've actually owned external HDDs for years but every now and then you have to update as new models come in and prices drop.

When I first started, prices were about £1.50 a Gigabyte and to get more than a 40 GB drive cost quite a bit. Prices are more reasonable now and it’s quite easy to own a 1TB 2.5 inch form SATA drive (£109 for a 1TB WD Passport from Pixmania!), more if you go 3.5 inch.

I've deliberately thrown in a bit of jargon there as it becomes important later on. There are a number of different makes of HDDs, models and sizes, both storage and physical size. They share 3 and sometimes 4 components. 1. A case. 2. A hard disk drive. 3. A USB or firewire cable, and 4. If it’s a 3.5 inch form hard disk, sometimes an external power cable.

The interesting thing about these setups is that you can place any HDD in any case so long as it’s the right physical size and the right type of bus connector. The lead is totally generic, the case is just that - a case and the only part that truly matters is the hard disk inside. You can purchase an internal HDD and a case completely seperately. This can save you money on the initial cost never mind on additional storage later on!

Jargon... buster

This is where the jargon comes in a bit. The most important part is the bus connection. There are basically two types of connection you can buy commonly. E/IDE (or P-ATA) and S-ATA. E/IDE or P-ATA is the older type of connector and up to the point of S-ATA pretty much ruled the HDD bus world. Essentially all it does is connect your HDD to the computer and allow data transfer from one to the other.

EIDE stands for Enhanced Integrated Drive Electronics. Groovy huh? S-ATA is a newer type of bus connector. The essential difference to you and I is that it is a faster data transfer speed that EIDE, it can function on a thinner but longer wire and it supports swapping out the component without shutting your system down, know as hot swappable.


I currently have 5 hard disks, variously bought with and without cases, repaired and salvaged from a dead creative mp3 player. I have two working cases. Most of my disks just act as back up storage, temporary storage or have loaded (older) games on them. I keep them safely stored when not in use and when I do want something on them; I put them into a case and plug it in. You don't have to buy external HDDs as a complete unit.

Once you know this, all you need is one or two working cases and that’s it. Every time you need more storage you can just buy a hard disk that fits into your case. An IDE connector is longer, and has two rows of pins that stick out. A SATA connector is smaller and has two plastic tabs with flat metal contacts.

Most of the cases sold are now SATA rather than EIDE so if you have an old hard disk or case you may need check carefully that they are compatible. A minor hiccup may also be in the depth of some 2.5" drives. Most of the disks are 9.5mm in depth but occasionally you get slightly thicker drives up to 12.5, especially in high capacity drives such as 1TB. You may have some problem fitting these into the case or if the fit is really bad, you may damage the pins.


The second hiccup is fitting the case adapter to the actual hard disk the right way round. In cases where this is fitted in, it tends to be just put the HDD in the case with the label upper most. In cases where the adaptor could easily go either way round, fit the block of pins into the connector and leave the 3 or four pins separate from the main block outside the adaptor.

internal HDD at 3.5" size
internal HDD at 3.5" size

Does size matter?

There are give or take 3 main sizes or forms of hard disk:

1.8” form: These tend to be only found in various hard disk storage mp3 players and possibly netbook type machines. You can get cases for these but unless you're after really small and portable, these aren't advisable. Small size means small components and small components tend to wear out and break faster. On the other hand, if you, as I did, have a drive of this size, you can get external cases for them and there’s no reason why they can’t be used as portable storage. There are smaller HDDs available down to about three quarter inch but I don’t know if there are cases available for these.


2.5” form: This size is commonly referred to as the 'laptop HDD' on account of them being used mainly for laptops. They're occasionally found in larger mp3 players as well, especially the older creative players such as the Zen xtra. (I have extracted two HDD’s from these players). Any player with a round figure capacity, such as 40 GB or 80 GB is likely to have a rotating HDD rather than solid state memory. (Incidentally, capacities of 1, 2, 4, 8, 16, 32 and 64 gigabytes are likely to be solid state memory players). This size of drive is the most available for the portable pocket drives. They run off the power supplied by the USB port (unless the case is very old and you may have a split lead type that needs two ports, one to supply additional power).

You will need to be careful of the type of connection. Older IDE type cases will not run a SATA drive. As far as I can tell, if it’s above 320 GB in size, it’s almost certainly a SATA drive. I currently own five drives of this size. Unless you’re looking for mega storage, this is the best size of drive to get. They aren’t hugely expensive, the cases usually come apart without the need for screws, and they are portable. These do range up quite high in size but at the top end, you will have to pay. Western Digital, Seagate, Hitachi, Samsung and Toshiba all do 1TB drives although you’ll likely as not pay twice the price as you would for a 3.5” drive of the same capacity.


3.5” form: These HDDs are the big 'desktop' drives. These are pretty much exclusively found in desktop computers, data storage banks and the likes. The components do not have to be as small which makes them cheaper to produce. The platters (the actual magnetic storage disks inside the drives) are physically bigger and can store more information. These are the most commonly produced HDDs and you can get terabytes of storage with these. Chances are, if the price is reasonable, say about 10p per Gigabyte, you'll be looking at a 3.5" form factor drive.

The pros of these are obviously, the capacity versus price. These are the cheapest drives by far and available in a very wide range of capacities. The cons of these drives is that they are a little on the large size to be truly portable and they invariably require a power cable for the case to work, the power cannot be drawn off the USB port. If the thing is just going to sit on your table and act as storage, consider one of these.


A quick mention to speed. The platters inside the HDD spin at various speeds. These range from old 4800rpm to a usual 5400rpm, through 7200rpm to some special types that spin at 10000rpm or faster (raptor drive is an example of this). This affects the seek time and general speed of data search on the disks. It probably won’t affect you at all if you have a 5400rpm instead of a 7200rpm unless speed of finding data on the disk is crucial to you. It will however be a more vulnerable drive to breaking if its high rpm, the price will be higher and the heat will be greater. Do you have the cooling for high rpm drive?

Final note. Buy actual HDDs, it’s cheaper and you don’t need all those cases. Check your EIDE vs. SATA connectors. Do store the spare HDDs very carefully, bash them around too much and they’ll die. Lots of HDDs ship with no formatting on them, you’ll need to look this up if you don’t know about it but it’s easy to do. Consider price versus size and remember a larger HDD is likely to have a better chance of survival.

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