How To Select An External Hard Drive!

An external hard disk is easy to use, since the drive can be written to just like an internal drive is attached to the computer. An external disk is relatively inexpensive, with models starting at around $150, compared to traditional data backup solutions. In addition, portable hard drives offer the ability to take data anywhere with you- since the drive weighs only a few pounds. Any user on the move that use a laptop or notebook will greatly benefit by utilizing an external hard drive. All of these features are compelling reasons to purchase an external hard disk. ´

But which one should you select?

There are many manufacturer and models. Well know brands as Maxtor, Seagate, Western Digital, LaCie, Iomega and Sony all produce removable hard drives.

External hard disk drives greatly differ in specifications, from model to model. Some models boast higher speeds, while others higher capacities. Some models offer different interfaces. Which interface is right for your needs?

This article will answer these questions, and aid you in your search for the perfect external disk drive.

Perhaps the most important specification on a removable disk drive is the size of the drive. External drives are typically rated in Gigabytes (a unit that means a billion bytes, which is the same as about 1½ CDROM discs), or GB. When selecting an external hard disk, you should first know what you will most likely be using the drive for, and about how much data you will be placing on the drive.

For instance, if you are planning on copying your digital photos to a movable hard drive (and you currently have to squeeze all of your photos on three different CDROMs), you may not require a 300GB hard drive. Instead, since your data backup would be just over a GB, an 80GB model would meet your needs.


When you review a disk drive, always multiply your current data backup need by at least three when looking for data capacity. For instance, if your data backups are currently 50 GB, do not buy a model less than 150GB. The primary reason for this is because your data storage needs will increase dramatically over the next few years, and you will want a drive that can handle these needs.

Once you have selected the proper capacity drive, you are ready to look at another specification- the cache size.

The cache size on an hard drive greatly controls how fast you can copy files to a drive. Cache is high speed memory on a drive which acts as a buffer between the computer and the drive. When data pours into the external drive, sometimes the drive cannot keep up with the incoming data stream. When this happens, the high-speed cache memory will temporarily store the data, so that the computer can still send data quickly.
Eventually, the drive will “catch up”, and copy the data from the high speed memory to the drive itself. This allows the computer to still send data as fast as it can to the drive, with no noticeable slowdowns. The larger the cache on the drive is, the faster the files will copy over to your drive.

On the other hand, since the high speed memory used for cache is very expensive, models with higher cache sizes are considerably more expensive than models with lower cache sizes. When selecting a drive, keep in mind the size of the cache on the drive. Once you have compared and picked a drive with enough cache, you should now consider which interface is the best for your drive.

There are primarily two different types of removable hard disk interfaces- USB and Firewire. USB, which stands for Universal Serial Bus, is an extremely common standard. With USB 2.0 support, your hard disk drive will copy files extremely quickly- assuming that there are no other devices using the USB card at the same time. The major drawback with USB is that the maximum transfer rate for the interface is determined by the other devices on the same interface. In addition, USB involves significant overhead on the computer, to send information over that particular interface. Firewire, on the other hand, can be considered a direct connection to the external disk drive, and will copy files much quicker to a hard drive than USB (given a large number of other devices using the USB card as well). Most external hard drives are capable of both interfaces- but some are only capable of either USB or Firewire. Bear in mind this important interface specification when you are selecting a movable hard drive.

Now that you know how to review and select the proper hard drive for your external backup and data recovery needs, make sure that what you purchase falls within those needs. Just because an item is on sale, does not make it a great bargain. However, if you shop wisely based on your backup needs, your external disk drive will be an asset several years down the road.