External Hard Drives vs. USB Flash Drives

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External Hard Drives vs. USB Flash Drives
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External Hard Drives vs. USB Flash Drives

The act of computing inherently requires the ability to both store information and process it. The first general purpose electronic computer relied on vacuum tubes and punch cards to store bits of information. This resulted in a very large and bulky system (one computer filling an entire room) compared to today’s standards. Currently, the task of data storage has been assigned to much smaller and more sophisticated technology. As time goes on, these information storage devices become smaller and are able to store much more data. This is now the age when one can store as much information on a piece of technology that is the size of the finger as was stored in a warehouse 60 years ago.

When searching for electronics, the buyer should have a basic understanding of what exactly is being purchased. In the case of portable data storage, the buyer’s needs will direct which device is best. This guide gives a fundamental explanation on the background and features of both the external hard drive and USB flash drive, a comparison of the products, an alternative that some buyers may find useful, and guidelines for purchasing on eBay.

Storage Devices Explained

Every computer has its own internal hard drive. The hard drive is a storage device, usually used as "secondary" storage, with an example of primary storage being the computer’s RAM (or random access memory). The RAM is used for computer functions such as running of the operating system, any open programs, and accessing information on the hard drive. The computer can only do one task at a time, and usually switches between multiple tasks very quickly to make it appear everything is working seamlessly and simultaneously. The RAM is what is performing these tasks, and the more RAM a computer has, the faster it can perform these tasks. The hard drive allows permanent and erasable data storage, while the data stored in the RAM is removed when the power is turned off.

A typical desktop computer hard drive consists of a magnetic disc, which spins to multiple thousands of rotations per minute, and an arm which writes and erases bits of information on the disc. It is an electronic and mechanical device, meaning there are moving parts inside. It can almost be thought of as a record player that is able to "erase" and "write" its own grooves into the record.

External Hard Drive

A useful way to store more data or to make this data portable without bringing the entire computer along is to utilize an external hard drive. The external hard drive works just the same way as the internal hard drive does. It is commonly of the same design and construction (with its own protective case that an internal hard drive would not have), and stores a similar amount of information. They are usually connected to the computer through a USB (universal serial bus) port and are compatible with most operating systems. An external hard drive shows up on the computer as another drive, just as the internal hard drive presents itself.

External hard drives are available in storage sizes ranging from 150 MB (150 megabytes, or 150 million bytes) to around 2 TB (2 terabytes, or 2 trillion bytes), but this is constantly increasing. These storage capacities lend themselves to a task such as backing up a computer. External hard drives can be found as a hard disc drive or a solid state drive.

USB Flash Drive

The USB flash drive, also commonly known as a memory stick, thumb drive, or disc on key, is a small portable data storage device. They are usually only an inch and a half long, with one end having the male USB plug and the other containing the solid state memory which is usually neatly packaged in a plastic case. Current offerings that are the most popular sizes can store between 500 MB to around 32 GB, though there are flash drives that store 1 TB or more and this is always increasing.

USB flash drives utilize flash memory (hence the name), which requires no moving parts. The bits of information are stored on semiconducting materials on a chip. While they are writable and erasable, their performance suffers after many writing/erasing cycles. They are small enough to be easily portable, and can fit on a person’s keychain. They are almost universal and ubiquitous and can be used by almost any current computer equipped with any operating system and a USB connection.

External Hard Drive Versus USB Flash Drive

Now that the basic functions of each option have been shown, the buyer can determine which one is better suited to the given application. The following chart goes over the relative advantages of both forms of data storage.


External Hard Drive

USB Flash Drive

Data Storage Size

Up to 2 TB and constantly increasing

Up to 32 GB are common, though they are available into the terabyte range

Physical Size

Approximately 1 x 4 x 6 inches cubed

Approximately 1.5 x 0.25 x 0.5 inches cubed


Fragmented memory, requires disc to accelerate to operating speed

Fragmented memory, limited write/rewrite cycles


Available since the 1990s, common in most large electronics stores and on eBay

Available since 2000, common in most electronics stores and other multi product stores (grocery), sometimes given out as advertisement method, easily available on eBay


Can fit in a briefcase or school bag, requires only USB cord

Can fit on a keychain, in a pocket, on a lanyard


Relatively heavy, disc drives are affected by shock and large magnetic fields, solid state drives unaffected by shock until components are broken

Relatively lightweight, uses solid state memory (shock does not affect performance until components are broken)

This side by side comparison should help shoppers decide between the two portable storage options.

Relative Benefits

The external hard drive has a much higher storage size to price ratio, is not significantly larger in physical size, can be as durable as a flash drive (if it is of the solid state design), and is just as available. However, the disc drive (if equipped) is susceptible to magnetic fields and impact. This type of drive is probably best used as a computer backup which does not need to be transported very often or for when very large amounts of data need to be moved from one computer to another.

The USB flash drive is highly portable, lower in overall price, highly available, and relatively durable. Its price point can be low enough (for the smaller memory sizes) that it can almost be considered a disposable item. As such, it is often given away by companies (along with other office accessories, including the company’s literature) at trade shows, job fairs, and similar events. However, flash drives have a finite number of write/rewrite cycles and performance can decrease after many cycles. This type of data storage is probably best used when a computer program based presentation needs to be uploaded to a conference room computer, when a digital photo album needs to be shared between friends, or when someone needs to take files from work home with them.

Alternative Option: The Solid State Drive

The solid state hard drive is a functional mix between the external hard disc drive and the USB flash drive. It can almost be thought of as a very large USB flash drive. Instead of using a rotating magnetic disc to store bits of data, it uses the same solid state memory principles as on the flash drive, also referred to as "flash" memory. It too suffers from the disadvantages of flash memory, being that there are only a finite number of write and rewrite cycles and the cost of flash memory is significantly higher than that of disc based memory.

Buying USB Flash Drives and External Hard Drives on eBay

Both the external hard drive and USB flash drive (and even the solid state hard drive) can be found in most office supply stores, large commercial electronics stores, and on various online shops, including eBay. There also exists a market for used and refurbished items. On eBay, drives have their own category within the Electronics portal. After clicking on Electronics from the main eBay page, hover over Computers, Tablets and Networking, and then click on Drives, Storage and Blank Media. From there you can choose hard drives or USB flash drives, and list items based on price, condition, and storage capacity, amongst other fields.

Know the Seller

Electronic devices tend to be considered relatively expensive, especially if they are new and contain fresh technology. When buying online, it is important to know where the electronics are coming from. Check the seller’s feedback, and make sure the description matches the photos. It would be worth taking a look at the listings from top rated sellers. If buying refurbished parts, don’t buy unless it comes with a factory refurbished warranty.


Cutting edge technology available to consumers will always be a bustling market, and that’s no different for electronic devices. With the portability, affordability, and demand of data storage devices being what they are, Internet shops and auction sites will continue to be a vital source for the consumer. As a buyer of a technical device, it is important to not only remain educated on the capabilities and performance of the device but also to understand the market. Considering the many listing and organizational features, buying through eBay can be one of the best ways to purchase the device that suits your needs best.

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