An external disk is in fact a hard disk, exactly like the one installed in your computer, except for two differences: it arrives in its own case which is external to the computer; and it is connected to the computer by a cable, usually through a USB interface.
In the past few years, important changes took place in this product category. The external disks have cheapened, their case has been improved, they are more reliable and come with longer warranty periods, designated programs and more. An internal drive will still be cheaper and a little faster, but external drives are easy to install and can be transferred to any computer, which is sometimes important.
Which drive will suit you? Our tips will help you decide.
The Important Questions
An external disk - who is it best for? An external disk is a great solution if you need additional storage volume and aren't interested in opening the computer, or there isn't enough space in the case for an additional disk. This is also a practical solution if you need a supplementary backup method or need to move large files often.
How Well Is It Suited For Backup? The external disk's unmistakable advantage is that when finished working it can be disconnected from the computer and locked in a closet or safe.
Even if the computer is stolen, burnt or crashes, your information is safe. Most of the external disks today arrive with special programs for automatic backup. On the other hand, an external disk isn't the most reliable backup medium. For small volumes, burning the data onto DVDs is the best method.
How Much Does It Cost? Today external disk prices start at around $120-$180 for small volumes of 40GB-80GB. For an additional $30-$100 you could receive a more sophisticated and faster product, in twice or three times the volume.
In which Case is it best to Purchase a Case and a Disk Separately? An external disk can be purchased in a closed case, or you can purchase the disk and case separately. The second option isn't necessarily the cheapest, although you could save the case and replace only the disk in the future. It could be worthwhile when needing the external disk for professional use and when investing in an especially high-quality and reliable case.
Things That Are Important to Know
In order to buy an external disk you don't really need to become an expert in the matter, but there a few things you should know. We've gathered the most important issues to consider, instructions and tips.
Get to know the manufacturers. There are literally dozens of products marketed in Australia today, the prominent manufacturers are Maxtor/Seagate, Western Digital and Hitachi (additional manufacturers: EZquest, Fujitsu, LaCie, Rocstor, Buffalo, Ippon, Archos, Tracstor, Philips and more). There are also differences in technology, but the differences that are important to most people are related to warranty (see below).
Pay attention to physical attributes. As a rule, you should distinguish between two different types of external disks: portable models, at a typical weight of 100-150 grams, which can be put in a pocket or bag.
They are very convenient but slower, a little more expensive, and considered to be less reliable.
The second type are external drives which are designated for "stationary" use, which can, at most, be occasionally transferred from one computer to another. They are big, fast and reliable; they can weigh from 700 grams to about 2kg.
What capacities exist? External disks can be found at any range of volumes that are customary in internal disks, and more. Among the portable drives there are models in small volumes of less than 20GB, which their advantage is mainly in small physical size.
What affects performance? The most important data related to hard disk speed is the rotary speed measured in rpm. Most of the new models support a speed of 7200rpm, like common internal disks. A part of the portable models support speeds that are less than 5400rpm or less. For "light" uses it's less important. If you need a fast disk which can store your music and movie files, its best to go for a faster model.
What interface? Most of the external disks sold today connect to the computer through USB 2.0 interface. There are few models in Firewire or eSata interface. The latter, assuming your computer supports them, will enable little improvement in performance, but they are also more expensive. Stay away from USB 1.1 models. Lately, designated models for multimedia purposes have started to penetrate the market, with audio/video outlets, possibility for direct connection to a television etc. but they are relatively expensive and there are still very few of them.
What cache volume? The cache also affects disk performance, although less than normally thought. The portable disks usually come with a 2MB volume cache. The external stationary models come with 8MB, and part of the models with 16MB.
What attached software? In many cases the programs that come with hardware products don't offer special advantages over those which can always be downloaded off the internet. In the cases of external disks there are exceptions, such as designated programs that the manufacturer provides to manage storage, backups, passwords and authentications. Not necessary, but not harmful.
Need security?In more prestigious models you'll find various security means, such as a mechanism for fingerprint identification, an integrated encrypting system, an automatic locking mechanism that is operated when the drive's case is opened and more. Look for these attributes if you're going to store sensitive materials on the drive.
Don't forget the warranty!Most of the external disks today, come with a two or three year warranty. Note that sometimes the same product is marketed at various suppliers with different warranty periods, and it's important to find out what the warranty covers – if in case of a malfunction a new drive will be provided immediately, or will you have to wait for the drive to be sent to the manufacturer.
Work within the recommended operating conditions! You should search the manufacturer's website for details regarding the environmental conditions in which the drive is recommended to be used. The parameter which has the biggest recognizable difference is the temperature of operation, part of the drives can survive a temperature higher than 60 degrees, while others prefer a more cool and shaded environment - up to 35 degrees.
It's less important for your computer and external drive to be in an air-conditioned room. If you need an external drive which could accompany you from place to place, resistance to high temperatures in the summer is certainly an issue to be taken into consideration. You're in Australia: choose a drive which can handle a temperature of at least 40 degrees Celsius.
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