The Dos and Donts of Buying External Hard Disk Drives

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The Do's and Don'ts of Buying External Hard Disk Drives

External hard disk drives (HDDs) are a great way to backup a computer and store large media files. These drives range in size both physically and in terms of capacity, from small portable units to heavy-duty storage devices. They come with a variety of features to suit the needs of buyers. With so many options available, choosing a drive may take some research.

There are five do's and don'ts of buying external hard disk drives. Firstly, buyers should investigate products and set a budget. They also need to know how much storage is needed and understand the technical specifications of the drives. Buyers should not assume that performance speeds are equal across products. They also should not overlook the importance of security. Finally, buyers should consider the availability of wireless drives. When shopping for external hard disk drives, buyers can visit the online marketplace eBay,, which has great deals on a range of computers, tablets, and networking equipment.

Do Research Products and Set a Budget

External hard disk drives vary significantly in their features and design. Buyers should always take the time to do a bit of research into the different brands and products to see the features that they offer, how reliable they are, and how much storage they supply. There are many manufacturers of external hard disk drives, but some produce products with a higher price tag than others. Some manufacturers may offer proprietary technology for security or deliver greater performance. Capacity and features also affect the price. Set a budget and be prepared to pay more for greater storage capacity, premium features, security, or extreme durability.

Do Know How Much Storage is Needed

External hard disk drives vary in capacity, but most newer models start at a 250 GB and go up to about 4 TB,, where 1 TB is equal to 1024 GB. For most people who need just a small amount of storage, a flash drive is sufficient. External hard disk drives are a better choice when backing up files or storing large media libraries, such as videos or audio collections. In fact, 1 TB of storage can hold more than 750,000 photos or MP3 files, or 230 films in standard definition. There are two kinds of external hard disk drives: those designed for desktop use and portable notebook-style units.

Desktop-Style Drives

Desktop-style drives are meant to be stationary. They typically require a power adaptor in addition to a connection to the computer. These are good for backup storage of a home or office machine. They tend to have higher storage limits because they are larger. Some models actually create a case for two or more drives in one unit, for a maximum 8 TB of storage in two 4 TB drives.

Notebook-Style Portable Drives

Notebook-style portable external hard disk drives are limited in their capacity when compared with desktop models, but they do not require an external power source, so are easier to travel with. Their capacities are frequently in the 250 GB to 750 GB range, but can be higher. Buyers should choose a style of external hard disk drive that reflects their needs and lifestyle; whether they want a heavy-duty storage solution or a small portable drive for use on the go. For example, if choosing a device to backup an internal hard disk drive, choose an external drive with a higher capacity. The same goes for units that are meant to replace other drives.

Do Understand the Technical Specification

One of the best ways to evaluate an external hard disk drive is to look at the technical specification. However, this requires understanding how a hard disk drive functions. Some internal drives have moving parts, particularly a spinning disk that stores the data. Two magnetic heads read and write the data to the disk. An external hard disk drive just has a casing that protects it from the elements. If this casing were removed it would resemble an internal hard disk drive in virtually every characteristic. Other key terms to understand are form factor and spindle speed.

Form Factor

Form factor does not refer to the size of the drive, even though it is stated in inches. A larger form factor equates to a larger drive. The largest form factor is 3.5 inches.. This is most commonly used in desktop-style external hard disk drives. One step down from this is a 1.8-inch form factor,, which is used in mobile electronics. The smaller the form factor, the more portable the drive, but expect a trade-off when it comes to maximum storage capacity.

Spindle Speed

Spindle speed, sometimes just called the revolutions per minute (rpm) of the drive, refers to how quickly the disk in the drive spins. Common options are 5400 rpm and 7200 rpm.. High-end models may have a 10000 rpm or 150000 rpm. A faster rpm generally translates into faster performance, but again there may be a trade-off in terms of storage capacity. Drives with a 10000 rpm and above are typically considered enterprise-class because they are speed oriented rather than for heavy-duty storage.

Don't Assume All Performance Speeds are Equal

Even if two external hard disk drives have the same capacity and spindle speed, buyers should not assume that their performance is equal. Data transfer speeds are often given in theoretical numbers, or how fast the drive could work under the optimum conditions, not real world conditions. How fast a drive can read or write data depends on several factors, including the drive's construction, the size of the files being transferred, and the drive's interface, or the way that it connects to the computer.


There are a variety of interface options, giving users plenty of ways to connect their drives to computers. Common choices are USB 2.0, USB 3.0, eSATA, and Gigabit Ethernet. For Mac computers, FireWire and Thunderbolt are popular choices. The table below lists the different interfaces and their maximum theoretical speeds. Speeds are given in either megabits per second (Mbps) or Gigabits per second (Gbps), with 1 GB equal to 1000 MB. Burst speed is the maximum speed for short periods; sustained speed is the maximum speed over longer periods. Hot swappable means that the device can be attached while the computer is running.

Type of Interface

Maximum Speed


Type of Computer

USB 2.0

480 Mbps (burst)

Compatible with USB 1.0/1.1 and 3.0

Universal Plug and Play enabled

Hot swappable


USB 3.0

4.8 Gbps (burst)

Backwards compatible with USB 2.0

Universal Plug and Play enabled

Hot swappable

Best for transferring large files and connecting other media devices



6 Gbps (sustained)

Secure connection rivalling internal drive performance

Best for transferring large amounts of data


Gigabit Ethernet

1 Gbps (sustained)

Versatile for networking purposes

Best for remote storage or transferring data over a network


FireWire 400

400 Mbps (sustained)

Hot swappable

Best for frequent large data transfers and media applications


FireWire 800

800 Mbps (sustained)

Hot swappable

Best for media applications



10 Gbps (sustained)

Can link multiple devices in a single daisy chain while maintaining speeds

Best for large data transfers and media applications


Many external hard disk drives are equipped with multiple interfaces, so they can choose whichever version suits their purpose. However, buyers should confirm the drive has the connections that they want, especially if they are looking for improved performance.

Don't Forget About Security

In the digital age, data security is essential. Cloud services can be accessed anywhere the Internet is present, but not all data is meant to be shared online. Physical drives can often complete data transfers and load faster than cloud storage solutions. However, even if the external hard disk drive is secure, it can be separated from the computer physically, so buyers should consider other security measures. Some drives are equipped with biometric scanners to prevent unauthorised access. There are also drives with built-in hardware encryption and password protection.

Physical data security is important too, especially if buyers are purchasing a portable drive. Some may be equipped with rubberised casings to prevent damage in the event of being dropped or bumped. Others may be made of robust materials. Certain drive models may even be waterproof or shockproof.. Consider the environment that the external hard disk drive is placed in when evaluating security options, whether digital or physical.

Don't Overlook Wireless Options

Some desktop models of external hard disk drives may be equipped with a wireless option.. This means that anything stored on the drive can be accessed by any device that supports wireless networking, including tablets, smartphones, televisions and DVRs. This is useful for media applications, such as sharing a music or video library. Some wireless drives are categorised as network attached storage devices (NASes), but they can still be considered external hard disk drives. Look for a device that also supports physical connections for the greatest amount of flexibility.

How to Buy External Hard Disk Drives on eBay

Consider shopping on eBay for external hard disk drives and all your other computing needs. The site is made up of a network of independent sellers. They depend on feedback from buyers to establish their reputations. Take a moment to create your own account on eBay,, which lets you complete your purchases, connect with other members, and provide feedback.. Signing into your account while you browse means that you can save searches, monitor items, and create wish lists of items that you would like to buy.


External hard disk drives are a great solution when buyers need a reliable backup device or heavy-duty storage. With their capacities ranging anywhere from 250 GB to several terabytes, they can accommodate even the most demanding media users easily. However, there are many factors to consider when choosing a drive.

Do always research products and determine a budget. It helps to know how much storage is needed and to understand the terminology used when discussing external hard disk drives. Although the specifications for products may be the same, buyers should never assume that data transfer speeds are equal, as they depend on many factors and vary from one model to the next.

Don't overlook the security features found on the drive, or disregard the possibility of a wireless option, which offers greater flexibility and allows sharing amongst several devices. Buyers can purchase a variety of external hard disk drives and other electronics equipment on eBay,, which offers convenience and great prices.

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