External Hard Drives


What is an external hard drive?

A hard drive is a sealed unit containing spinning magnetic disks with heads that can position themselves anywhere on the disks to read and write data to them. Think of it as a record player that can both play and record music. Most hard drives are internal, buried deep inside desktop and notebook computers. Replacing an internal hard drive is tricky and should be performed only by someone who knows what they’re doing. However, external hard drives are simple enough for anyone to use.

External hard drives are basically the same as the internal hard drives you would find inside of computers housed in an enclosure with a USB, eSATA or FireWire port. The enclosure protects the bare drive and provides power and data ports to it. An external hard drive makes it easy to add more storage space to a computer without having to open it up. It’s like putting a storage shed in your yard when your basement becomes full. External hard drives also make it easy to transfer data from one computer to another.

How much capacity do I need?

The first thing to consider in an external hard drive is capacity. External hard drives have capacities typically ranging from 250GB to 2TB, and a lot more if the unit contains more than one drive.


If you’re in need of an external hard drive because your computer’s internal hard drive is full, buy one with at least double that capacity. To make your buying decision easier, consider that the smallest external hard drives available now have capacities of 250GB, followed by 320GB and 500GB drives. And because you can never really have too much space, your best bet is to buy the largest-capacity drive that fits your budget. If you need even more storage space than 500GB drives offer, external hard drives with expanded capacities of 1TB and more can now be acquired.


Do all external hard drives offer the same performance?

The disks inside bare hard drives spin at a certain speed, and the faster they spin, the faster data can be written and read. Most hard drives spin at 5,400 rpm and 7,200 rpm, the latter usually outperforming the former. Note that high performance, 10,000 rpm and 15,000 rpm hard drives are used in servers, workstations and other applications in which performance is critical, but you won’t find those rotational speeds in consumer grade external hard drives.

Higher-capacity drives tend to spin at 7,200 rpm simply because they use newer technology, but don’t shy away from something simply because it’s only 5,400 rpm. Sometimes you’ll even see the same basic external hard drive available in both rotational speeds. If you often find yourself copying multiple gigabytes to an external hard drive, the faster spin speed will save you some time. However, if you rarely copy that much data, then it’s better to shop by price and forego speedier performance.

Solid-state hard drives, or SSDs, are not your conventional hard drvie. Instead of spinning disks, SSDs contain flash memory chips and no moving parts. Some SSDs are faster than conventional hard drives, and all are more resistant to shock and vibration, but you pay a lot more per GB of storage space and SSDs don’t offer nearly as much capacity as conventional hard drives do.


How big are external hard drives?

Bare hard drives come in two basic sizes: 2.5-inch and 3.5-inch. The 2.5-inch drives are used in portable notebook computers and portable external hard drives, while the 3.5-inch drives are used in desktop computers and desktop external hard drives.

Using 2.5-inch hard drives in portable external drives makes sense because they allow for a smaller, lighter unit that uses less power. Portable hard drives will fit in a shirt pocket, provided your shirts have relatively big pockets. Regardless, portable drives are much smaller than desktop drives, so if you often have to carry one with you, portable external hard drives are the way to go.

Because portable hard drives are often ported from place to place, they run the risk of being dropped from time to time. For that reason, some manufacturers offer portable hard drives with rugged enclosures. These contain the same basic drives as non-rugged units, but they feature shock-absorbing enclosures, usually made of rubber, that protect the drives from the daily bump and grind. But be warned that these will break if you abuse them enough.


Portable hard drives are typically bus powered; meaning that they receive power from their interface cable, so no AC power adapter is needed. This lets you use the drive with a notebook computer when you are nowhere near an AC outlet. It’s also one less thing to pack and carry.

Desktop-size external hard drives contain 3.5-inch drives, making them bigger and heavier than portable units, and they also require an AC power adapter.


What types of interfaces are available?

There are several types of interfaces, but the type of interface, or port that your computer has will largely determine the type of interface you need on an external hard drive. Most Macs have FireWire, while most PCs don’t. Apple has also introduced the Thunderbolt port and the few external hard drives with this new port are very expensive because of the high data-transfer rate of 20Gbps. But all computers have USB 2.0, and some of the latest ones now have USB 3.0.

USB 2.0 is by far the most common interface found on today’s computers, which is why it’s also the most common interface found on external hard drives. USB 2.0’s maximum throughput is 480 Mb/s, or 60 MB/s, but you’ll typically see only 30-35 MB/s in real-world applications. If your computer has USB 2.0, you can safely invest in a USB 2.0 external hard drive with the assurance that you can connect it to just about any computer in the world.


Basic drives have only a USB 2.0 port.

Some external hard drives now feature a USB 3.0 interface. USB 3.0 is specified at 4.8 Gbps, or 614 MB/s, but you’ll see about 400 MB/s in real-world use. While most computers don’t yet have a USB 3.0 port, USB 3.0 is backward-compatible with USB 2.0. So you can invest in a USB 3.0 hard drive, use it now with a USB 2.0 computer at USB 2.0 speeds, and reap the rewards of faster throughput once you buy a computer with the faster USB 3.0 interface. Some USB 3.0 external hard drives come with a USB 3.0 interface card, and you can always buy a card separately if a drive doesn’t come with one.

This drive has a USB 3.0 interface.

FireWire 400 provides 400 Mb/s, or 50 MB/s throughput, and FireWire 800 doubles the throughput to 800 Mb/s, or 100 MB/s. If you work primarily with Macs, FireWire is the way to go. Some newer computers have eSATA, or external Serial ATA ports, for connecting external peripherals such as hard drives. eSATA is as fast as internal SATA, providing 3 Gbps, or 384 MB/s throughput, or closer to 300 MB/s in use.

Here’s a triple interface with USB 2.0, FireWire 400, and FireWire 800.

Here’s one with eSATA and USB 2.0.

External hard drives with only eSATA interfaces are rare, but many external hard drives have various combinations of ports, including USB 2.0, USB 3.0, FireWire 400, FireWire 800, and eSATA. If you buy a triple- or quadruple-interface hard drive, you can rest assured that it will connect to any computer that’s out there.

The very latest type of interface, called Thunderbolt, was developed by Intel and brought to market by Apple, and now offered in some of the latest MacBook Pro models. Thunderbolt basically combines PCI Express and DisplayPort into a single interface that offers data transfer rates up to 10Gbps. For anyone lucky enough to have a computer with a Thunderbolt port, a handful of external hard drives featuring Thunderbolt ports are available.

What can I do with my old hard drive?

If you have an old computer that you’ll never use again but its hard drive is still good, or if you upgrade the hard drive in your desktop or notebook computer and don’t know what to do with the old drive, you can always install it in an enclosure that will convert it for external use.

You have to know whether the drive is a 2.5-inch or 3.5-inch unit, and whether it’s Parallel ATA (PATA) or Serial ATA (SATA). If it came out of a notebook computer it’s a 2.5-inch drive and if it came out of a desktop computer it’s probably a 3.5-inch drive. If its connector looks like the one below on the left it’s PATA and if it looks like the one on the right it’s SATA.

B&H carries a wide variety of hard drive enclosures for 2.5-inch and 3.5-inch drives. Most of them are for SATA drives only, but some will accept SATA or PATA. The only other decision you have to make is what kind of interface you need on the drive enclosure. As mentioned before, USB is nearly universal and very common on PCs. FireWire is more common on Macs.


What is a multimedia hard drive?

If you’re into multimedia, there’s a special kind of external hard drive that will surely appeal to you. Multimedia hard drives are typically used to store video and play back the video on an HDTV set. They feature component and HDMI video outputs and come with a remote control, so that you can enjoy your entire digital multimedia collection on the big screen.

Is encryption important?

If you keep top-secret or personal files on your external hard drive and there’s a chance you could lose it or that it might get stolen, you will want a unit with password protection and data encryption. Encrypting your data prevents unauthorized users from accessing it. In other words, if someone doesn’t have the right password, they can’t get at the data. Some drives use biometric authentication to protect the data. With this configuration, your fingerprint is used for access instead of a password.

Do I need redundancy?

When a hard drive fails, you usually lose all the data stored on it. While most external hard drives contain just a single drive, some contain two or more drives and use RAID technology to increase performance and capacity or to provide data redundancy.

Most of the external hard drives that feature RAID technology support RAID 0 and RAID 1. RAID 0 splits data evenly across two or more disks to increase performance or to create a single virtual drive from multiple smaller drives. Basically, this gives you one drive letter instead of many. RAID 1 creates an exact copy, or mirror, of a set of data on two or more disks so that if one drive fails, the data can be recovered from the healthy drive(s). Note that duplicating all of your data on two separate external hard drives will give you the same peace of mind.

What is automatic backup software?

Most external hard drives come with some sort of automatic backup software that makes backing up your data a little easier. You can usually set the software to back up your computer on specific days and times. Just keep in mind that you have to leave your computer turned on for the times when you have backups scheduled.

The Takeaway

  • Get an external hard drive with the largest capacity you can afford.
  • Look for an external hard drive that spins at 7,200 rpm if performance is important. Otherwise, 5,400 rpm is fine.
  • If you will be traveling often and have a notebook computer, get a portable external hard drive. If you have a desktop computer and need an external hard drive for the home or office, a desktop unit should suffice.
  • Look for an external hard drive with a USB interface if you work with PCs, or FireWire if you work mostly with Macs. Get one with both interfaces if you need to transfer data between the two platforms, or just get one with a triple or quad interface if you often work on different computers.
  • Look for a multimedia hard drive with component and HDMI video outputs and a remote control if you want to store and play it back video on an HDTV set.
  • If security is your primary concern, look for a drive with password protection and data encryption to prevent unauthorized users from accessing your files in the event you lose it or if it is stolen.
  • Look for a unit containing at least two hard drives and configure them into a RAID 1 array so that you don’t lose data if one of the drives should fail.
  • Look for a drive that comes with automatic backup software if you want to back up your computer on specific days and times.

Items discussed in article

Discussion 14

Add new comment

Add comment Cancel

SUPER Helpful!! Thank you!

I'm in the market for an external hard drive for picture storage. Most external hard drives seem to be primarily for backup of data, and many of them don't have "drag and drop" capabilities. I just want to easily transfer many gigs of jpeg & raw files to and from an external drive, and to even open files that are on the external drive in Photoshop. Can you recommend such a drive, up to 1TB capacity, that allows for this? Thanks for any help with this...

When you purchase a hard drive, you will be able to use it for many tasks. Backup is only one of them. A drives main job is to hold information, and it does not matter what that information is. When you plug in an external drive, any modern operating system (Like Microsoft Windows or Mac OS) will provide you with the support to drag-and-drop any file type to and from it.

Depending on the computer that you are using, it will have different ports to connect an external hard drive, and this in part will determine the speed of the drive. I bring this up because you are looking to open files, and edit them directly from the drive. In your case, with the average Photoshop file size, a USB 2.0 connection would be more than sufficient.

Some of the faster connections would be Firewire 800, USB 3.0, eSATA, and Thunderbolt.

Also, drives of that capacity are available as a desktop form factor, or portable.  The desktop drives tend to be less expensive, but will need to be plugged into the wall for power. Portable drives are Convenient, and most are powered by the connection to the computer (USB, Firewire, etc…)

A portable USB 2.0 drive like the Western Digital 1TB WD Elements Portable SE Hard Drive is a very good value.

For a desktop drive the 1TB Touro Desktop USB 2.0 Hard Disk Drive is also a good value.

If your computer supports Firewire 800 the 1TB My Book Studio or 1TB eGo from Iomega are both very reliable drives.

anyone know the best resources for memory sticks? just trying to find the best deals. will be buying in bulk.



Hello -

B&H offers a variety of brands/models of memory stick flash media.  We may be able to help you with a bulk purchase.  Please send your request for a quotation via e-mail to sales@bandh.com

I have purchased a Seagate Goflex Desk ext Hard Drive, 3T. I would appreciate your advice. I simply want to copy with mirror imaging. I do not want encyption. I use Windows 7 on a PC, and Lightroom 3 or 4.
How do I set this up on the computer and the external HD? Thank you.

Hello Bruce -

Check out the The 1TB G-Drive External Hard Drive from G-Technology is a high-capacity external hard drive. It features a 7200rpm rotation speed and an interface that allows it to be connected via eSATA, FireWire-800, or USB 2.0. It can connect via FireWire-400 using the included FireWire-800 to FireWire-400 cable.

Thank you B&H for this excellent tutorial...and for all you've done for photographers over the years...

I remember standing in a long line at your 17th Street store, 100 dollar bills in hand to buy supplies

for my business... The only place in town to get the right price on everything photographic...

Times have changed and while B&H is world renowned, it is no longer the least expensive place

to buy, but reliable and friendly, the benchmark that Ken Hansen established is still in


I will always check your inventory before I buy anywhere in the world...

Thanks again,


very helpful

exelente nota, los felicito!!!! felices fiestas.

This article was very helpful, thanks!!

Is there any hardware/software available to connect three 500 Gb external backup drives and create a "virtual" 1.5 Tb backup drive?

I'm looking for software or other option to MIRROR hod's.
I'll eventually purchase a Drobo, But until then & also after that for redundancy, I want to Mirror or Raid my External Drives.
What options do you suggest?
I've seen a few free & pay versions on the web, but not sure on one yet.

I'm currently using a 15" MacBookPro w/ Retina Display.

Any Suggestions would be helpful.

I also have a few other computers that are PC's.

I have a 3.5inch Sata2 x 1TB  HD which is in an external fanned case. I have connected it to my Laptop, via USB, which has updated the drives for it. I previously used it for recording CCTV which was a failure. I would like to view the HD but cannot find a command to open it.

I have tried Devise Manager which states that the driver software is up to date and that the size is 1.03KB and size on disk is 4.00KB.

 This I cannot understand as when it was attached to the DVR, it showed a recording of 30+- KB ( I think).

Can anybody help me with this problem.

Regards David.