18 Pros and Cons of External Hard Drives

backupsoftwareforharddrivesbannerIn this detailed article we discuss the advantages and disadvantages of external hard drives, connected via USB, eSATA, or Firewire. With the advent of USB 3, all modern PCs, servers, and laptops now offer a very simple interface for plugging in portable storage and as we summarize below, external hard drives are perfect for dozens of uses.

The pros and cons of external hard drives vary, however, so you may want to consider all points below before making a purchase. And, perhaps, this article may help you come up with ideas of how you could use your existing USB drives in new ways. Many BackupChain backup software customers use external hard drives for backup purposes and replaced tape drive with disks. They are a great way to save money and time; however, every technology has its pros and cons.

If you have additional ideas not listed below, feel free to email them to us for inclusion. Thank you! Also, if you are associated with a university, we offer huge discounts for academic institutions and non-profits who purchase BackupChain backup software. Contact sales for a quote!

Advantages of External Hard Drives

Lowest cost per GB: hands down, there is no cheaper storage than external disk storage, when you consider the additional benefits they offer over burning CDs, DVDs, and Blu-ray disks. Yes, the material cost of optical media is lower but realistically the labor required needs to be considered as well. In addition, optical disks are very prone to errors and don’t last as long as they should (More details are available here: //backupchain.com/why-you-shouldnt-use-optical-media-for-Backup.html)
Today in 2014, a new Seagate 4TB drive costs under $140, that’s just 3.5 cents per GB!

Space: The major downside of CDs, DVDs, and even Blue-ray when used for storage and backups, is that they offer very little space to work with. Today you can buy a 6TB external hard drive that holds about 9,000 CDs in a small 3.5” drive! The life expectancy of a CD is just under three years, whereas a shelved hard drive will definitely outlast it and provide you backup speeds of over 150 megabytes per second (= 9 GB per minute).
Whenever you need additional backup storage space, simply buy another USB drive. External disks may be combined and even structured into a pseudo-RAID using Windows Storage Spaces  on Windows 8 and Windows Server 2012, see this how-to article  https://www.winhelp.us/storage-spaces-in-windows-8.html

Ease of use (connect disconnect): Everyone should have an external drive for backups when a centralized backup server or NAS backup device aren’t available. USB and eSATA drives are very easy to move from PC to PC as needed. Using the Plug-and-Play functionality you can plug the drive it and the system recognizes the partition automatically. Installing an internal drive, on the other hand, isn’t something everyone can and wants to do.

Portability: USB drives are portable in many ways.
Physically portable: you can move lots of terabytes in lightning fast by unplugging the drive and plugging it in to a new PC or server. Imagine how long it would take to copy 6TB over the network or over the internet!
Portability between systems: Different kinds of OS and PCs / Macs all support USB drives; hence, you can copy data between dissimilar operating systems by just plugging in the storage directly to it.

Easy replacement: Imagine your main hard drive breaks. No you wouldn’t want to imagine it, unless you already made that experience. It’s a disaster and takes a lot of time. A USB drive is replaced within a minute. Having good data backups is of course a different story. If you don’t back up your external hard drive you’ll still lost data…and end up in a disaster.

You can buy many and expand as needed.  In order to max out your server or PC to, say 20TB, all you need to do is buy a bunch of USB drives. Ideally you would want to attach them to separate USB controllers for better speed but even on the same bus it works fine.

Speed!  Speed is a gigantic advantage of portable drives. We see well over 150MB/sec read and write from a single drive. If you RAID them in a stripe layout, each drive adds 150MB. Use four together in a USB enclosure that supports RAID and see transfer speeds reaching 600MB/sec!
Backing up data to CDs and DVDs is more like turtle speed compared to a modern USB3 external hard drive. You can copy an entire music CD in a couple of seconds. When backing up your main hard drive, this means finishing up faster; less downtime; less hassle; less waiting; and, potentially, as a result, more frequent backups!

External Hard Drive Storage Can Be Combined. External hard drives are supported in Windows Storage Spaces, a new technology included in Windows 8 and Windows Server 2012. Some speculate it’s a feasible alternative to RAID http://betanews.com/2014/01/15/windows-storage-spaces-and-refs-is-it-time-to-ditch-raid-for-good/

Simple Rotation: For backups as well as storage, you can easily deploy rotation using USB hard drives.  The Backup Rotation Scheme (see //backupchain.com/Backup-Rotation-Scheme.html)  is a popular and low-cost strategy to make reliable backups with no single point of failure. Put one drive in a safe and have the other one plugged in. Let the backup software do its thing at night. In the morning unplug and swap the drives. Want to make it perfect? Use a third drive and keep it at home, away from the office. No configuration is necessary, just plug and unplug, add and remove as needed!

Isolation: USB drives are really awesome in many ways. Another major advantage is isolation. USB drives can be unplugged and put in a safe so that they are completely isolated from the PC or server. If a virus or power surge destroys your equipment, the drive will be fine and ready to go for a restore operation. Many users keep the USB drive always plugged in, but unless you’re using a backup rotation scheme, it’s a mistake. The drive is exposed to wear-and-tear, vibration, virus damage, and power surge risks. When kept in a safe, it’s completely isolated even against small floods. A famous guy once said, ‘only the paranoid survive’. If your data is really important, you won’t find the idea of isolating the drives paranoid at all.

Unlike NAS, external hard drives can be used and formatted like an internal drive: This is another huge advantage. Yes, you can use network servers and NAS backup devices and access data over the network from a centralized source. It’s much more convenient, however, in a single user environment, to use an external drive. First of all, it’s so much easier to use than a network. Second, the network introduces latencies and speed issues, and requires management and maintenance, too.


Summary of all advantages:

External hard drives are perfect when used as backup storage media, and a great alternative to tapes, CD, and DVD backup. Tape backup is rapidly losing out to external hard drive backups. This is simply due to the reasons listed above, including costs and ease of use. Many disadvantages of tape backups have been eliminated by using USB external drives; however, each technology has its own pros and cons. For many SMBs, external hard drives are the perfect storage media for virtual machine backups.

Disadvantages of External Hard Drives

Speed: Speed is actually a main advantage listed above as a pro, not a con, but there is more to the story. Especially when many drives are on same USB bus, data throughput speeds will deteriorate because the bus is being shared. Ethernet has the exact same issue. It’s cheap and as you add more PCs to the same bus, the probability of packet collisions grows rapidly and that in turn slows down the entire link for everyone. When speed is very important you should really use eSATA or an internal drive instead. Perhaps a software RAID may be a good solution, too, if you don’t want to invest in expensive RAID controllers. But for most users, external hard drives are very fast, more than just fast enough.
External Hard Drives Can Break Easily: This is a major disadvantage. You can easily break the external drive by dropping it. Electrostatic discharge is another common issue in the winter time. See //backupchain.com/16-things-that-destroy-your-files-and-your-computer.html
Unfortunately the drive isn’t protected by a sturdy case like your PC so extra caution is necessary.
Back in the early 1990s we had 40MB hard drives that required a manual ‘park’ command to move the hard drive heads to a safe corner so they don’t hit the plates when being transported. Fortunately this isn’t an issue anymore with modern drives. The risks of a head crash and magnetic interference remain, however.

Overheating:  Internal drives are usually installed in a way that permits proper cooling via case fans. With some USB external hard drives out there, overheating may be an issue. In the summer and under heavy use, hard drives may heat up to about 50 degrees C or even more. You’ll need to choose a device with a good passive cooler design and place it away from the sun and other heat sources, ideally with good ventilation.

No RAID. Usually no RAID mirror or stripe is offered in a USB drive, but some enclosures and controllers do have that function built-in. Windows Software RAID doesn’t support USB drives, but Windows Storage Spaces do. Another workaround is to buy a NAS backup device and use it via USB3.

Theft: Corporate clients are usually very cautious about external hard drives. The theft potential is very real as these tiny drives are very easy to steal and conceal. While at lunch, a colleague may take your drive or a disgruntled employee may copy all client databases to a drive and take it with him before quitting his job; hence, the drive itself may be stolen, or it may become an aid for a thief. These are real-world issues and potentialities to think about as a business owner.

Exterior cabling and power adapters (for 3.5″ drives) are necessary: Say you have 3 or 4 external disks on your desk and each needs a USB cable and a power cord. You now have a problem: lots of cabling on your desk and your Uninterruptable Power Supply, aka battery backup, doesn’t have enough receptacles! And many users will moan their desk looks “unprofessional” with all those cables—granted, it’s not the neatest way and certainly not suited for the CEO. In addition, you’ll need more receptacles even if you’re not a CEO.

Accidental interruption. The more USB devices you have, the more likely it is you may unplug the wrong one at the wrong time. Luckily Windows uses a short timeout to flush out write operations to the external hard drive quickly so you won’t lose as much information if you unplug the drive accidently. But if you have some important data on the drive, unplugging at the wrong time may corrupt it.
Accidental interruption also occurs when your computer is backed by a battery backup device and the external hard drive is not. Short, unnoticeable power cuts occur all the time and are long enough to break and even destroy your USB drive. At the very least the power cut will drop the link from PC to external hard drive and cause an error, potentially even corrupt the data file.
Hence, use a battery backup device for your external hard drives, too, and once it’s ON, “you can’t touch this!”

Booting Windows from an external hard drive: The last disadvantage of external hard drives is you cannot boot Windows from them. Some “hackers” have figured out ways to do it but it’s generally not recommended, nor will you be satisfied with the performance. We have seen people boot virtual machines from USB hard drives and work on them. That seems to be working well and offers employees a way to take the virtual machine home if need be.

What About Backups and Backup Software for External Hard Drives?

External hard drives are almost perfect for backups, but if you actually store your work on an external hard drive, it should be backed up, too. When connected to a USB3 or eSATA interface, the transfer speeds are close to an internal drive, so you could run the backup process often without wasting much time. However, many users forget to back up their work because they do not use automated backup tools. When you use professional backup software, such as BackupChain, not only does it come with a task scheduler so you don’t have to remember to run your backups, it also uses logging to track every single file backup, in case something goes wrong.

When you use external hard drives for backup purposes, there are several things to watch out as some drives may break file transfers intermittently: use a good quality cable (same applies for internal drives), and a good quality USB hub, if you need one. Some USB controllers become unstable under high load, too, so if you see hard drive connectivity issues, you may need to swap out one item at the time to find out what causes the issue.

List of Manufacturers


Intel SSD Drives

CMS Desktop Hard Drives


IBM Storage Systems





Kanguru Portable HD

Apricorn Portable External Hard Drives





Buffalo Technology

Fujitsu Hard Drives


Western Digital


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