The Complete Guide to Buying External Hard Disk Drives

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The Complete Guide to Buying External Hard Disk Drives

External hard disk drives provide computer users with the ability to easily add storage capacity to computers in a relatively inexpensive manner. External hard disk drives allow individuals to have an infinite amount of storage that can be added on as needed, and with plug and play capabilities, external hard drives offer ultimate convenience. External hard drives solve the problem of having to upgrade a computer that has gone beyond its built-in storage capacity.

For many computer users, installing an additional hard drive into the computer, regardless of how easy it might be, is something that they are not comfortable performing. Additionally, upgrading a computer through a professional can be costly and prevents use of the computer during the upgrade. The solution is to purchase an external hard disk drive. Once individuals understand the different types of external hard drives available, their capabilities and ease of use, and how easy and affordable they are to purchase on eBay, the decision to purchase an external hard disk drive becomes easy.

Uses for an External Hard Disk Drive

External hard drives increase the storage capacity of computers, and they are also excellent for backing up computer system files. External hard drives can be programmed to perform a system backup on a regular basis automatically, so the user always has sensitive data safely stored on the external drive should something happen to the computer. External hard drives offer users the peace of mind that comes with knowing that they are protected from losing their important files.

Another important use for external hard drives is the portability of data. Portable external drives come in very small sizes that make it convenient for users to download data from one computer and transfer it to another machine in a different location. This is helpful for individuals who work on two different machines in different locations and need to keep the data up-to-date in both locations. External hard drives also make it convenient for users to share videos and photos with friends and family by allowing them to download the contents of their external devices onto other machines.

Types of External Hard Drives

There are two different types of external hard drives available to the consumer for added storage capacity. Different brands, styles, performance capabilities, and storage capacities are available to the user, but all of them fall within one of these two external hard disk drive types.


Desktop-style external hard drives are the larger of the two types of units, and they are designed to be kept in one place near the computer. Desktop units require an external power source and come with their own power adapter to supply power. External desktop hard drives are the larger of the two variations of drives. Because these drives are intended to be kept in one place, they feature large amounts of storage capacity. Desktop units are available with internal fans, which are helpful in cooling the device when it is in constant use during operations such as backing up large amounts of data or video. Desktop units range in size, depending on how much storage capacity they have and whether or not they include an internal fan. Generally, the larger the storage capacity and the higher the performance level, the larger the unit is.

Portable External Hard Disk Drives

Portable external hard disk drives are designed specifically to be moved from location to location. Portable drives are used mainly as backup and additional storage for laptop computers and notebooks. Portable drives are considerably smaller and more compact than desktop hard drive units. A portable hard drive is powered through the connection to the computer so it does not require its own source of power or an adapter. This furthers the convenience factor of these units and, along with the small size, makes them very useful for data storage and backup on the go. Portable units are also ideal for transporting data from one location to another, and a unit can easily fit into a purse or a coat pocket.

Storage Capacity

External hard disk drives have storage capacities that typically range from 100 GB of storage in the smaller portable units up to 8 TB in the larger desktop drives. The amount of capacity a user needs is determined by the uses for the external hard drive. For units that are utilised strictly for additional storage, a good general rule of thumb is to buy one that has at least twice the capacity of the computer.

Data Term

Size of Data

1 byte

8 bit

1 kbit/s

1,000 bit/s

1 Mbit/s

1,000,000 bit/s

1 Gbit/s 

1,000,000,000 bits

1 kB/s

1,000 byte/s

1 MB/s

1,000,000 byte/s

1 GB/s

1,000,000,000 byte/s

1 TB/s

1,000,000,000,000 byte/s

Portable units used mainly for transporting data or backing up laptops usually have smaller capacities to accommodate the compact size. The amount of storage capacity of the external drive really depends upon the needs of the user. People who store large amounts of pictures and videos require a larger storage drive than someone who only stores text files. Many people do well to purchase the largest amount of storage they can afford to accommodate storage space needs that might arise in the future.

Performance and Connectivity of External Hard Disk Drives

External disk drives are usually rated on how fast the disk drive spins. The faster the spin speed, the quicker the data can be written to it. How an external drive is connected to the computer can also vary, and the different connections transfer data at different speeds and quality. The variety of connections available for external drives allows them to be used by different types and generations of computers.

Spin Speed

The 5400 rpm hard drive spins slower than the 7200 rpm version, and it is less costly to purchase. The 7200 rpm drive is able to write larger files and data quicker than the 5400 rpm version, which is helpful for users who copy large amounts of data on a regular basis. However, the 5400 rpm version is adequate for general computer usage and is a good choice for users on a tighter budget since the 7200 rpm version is more expensive. If speed is the important factor, then the buyer should give consideration to the 7200 rpm hard drive.


USB 2.0 and 3.0 are simple plug and play connectors that allow the user to plug the external hard drive into a USB port for instant connectivity. USB 2.0 is the more common interface found on computers, and it has the capability of transferring data at a maximum speed of 60 MB per second. USB 3.0 is newer technology that is not available on every computer, but it is backward compatible, so it can be used with both 2.0 and 3.0 machines. USB 3.0 transfers data at an average speed of 614 MB per second, so it is considerably faster than USB 2.0.

FireWire 400 and 800 are present primarily on Macintosh systems and are similar to USB in terms of connectivity. FireWire 400 transfers data at 50 MB per second, and the 800 transfers it at 100 MB per second.


eSATA stands for external serial advanced technology attachment, which means that it is an external version of the same type of cables that are used to connect internal hard drives to the motherboard for quick and stable data transfer. eSATA connections operate at a speed of 384 MB per second and are plugged into the computer much in the same manner as USB and FireWire.


External hard disk drives are convenient and powerful devices that can add more storage to computers or back up critical data. An external hard drive can be placed in a fixed location that is always connected to the computer, or it can be a portable unit that is attached to a laptop only when transferring data or backing up files is required. As technology improves, the cost for external hard drives continues to drop, and the amount of storage increases. Advances enable greater storage capacity in smaller devices, both portable and stationary, and the reduced prices enable people to upgrade their storage needs while staying within their budgets.

Buyers who are interested in purchasing an external hard disk drive should take the time to understand the different types of units available and the types that suit their needs. The various speeds and capacities available as well as the different connection capabilities that external drives come with mean that some research is needed on the buyer's part. eBay is a great place to accomplish this research and find great deals on the external drives available.

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