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Additional internal drives have a role, but with external hard drives being cheap and common, adding storage to your system can be very quick and easy.

I have a 80 GB hard disk in my system. I'd like to upgrade the storage capacity. Which is a better option: getting an external hard disk or internal hard disk?

It depends.

It depends on how you use the machine, how comfortable you are installing hardware, and how much effort you want to go through.

Let's add "replace the existing hard drive" to the mix, and review all three options.

Add an External Drive

Adding an external USB (or Firewire/1394) drive is by far the easiest approach. Purchase the drive, set it up, plug it in, and you've instantly increased your storage capacity by however large a drive you purchased. It's a perfect solution for many needs.

The biggest downside to this approach is speed.

USB 2.0 is rated to 480 Mbps - that's (approximately) 480 million bits per second. That sounds fast (and it certainly is much faster than USB 1.1's 12 Mbps), but it's slower than the transfer rates afforded by the hard disks themselves. A good average transfer rate from a hard disk these days is 700 Mbps, or nearly twice as fast as that data could be transferred over a USB interface.

"Adding an external ... drive is by far the easiest approach."

That USB 2.0 480 Mbps is also a theoretical maximum, and can quickly be degraded by the activity of other USB devices connected to the machine. (Firewire/1394 connections suffer this same complication, but benefit from there not being as many Firewire devices. In addition, some Firewire interfaces can support a maximum of 800Mbps, and thus may be able to keep up with typical hard disk transfer rates.)

Other "complications" of a USB drive are the additional power and connection cables required, the fact that it's an additional box to be placed near your computer, and the fact that the drive will appear as an additional drive letter on your machine. These aren't big problems at all, but worth noting.

Overall, if your needs are not typically disk speed intensive, an external hard drive is often the simplest solution.

In the coming months, external drives may take on additional appeal as ESATA and USB 3 interfaces become more common. These interfaces support transfer rates that are actually faster then the typical hard disk drive, and thus should presumably make external drives as fast as the alternatives.

Add an Internal Drive

Installing an additional drive into your machine is the best way to get the maximum performance out of a new drive. It also removes the whole problem of having an additional external box that you need to plug in somewhere.

You'll need to make sure that your computer has room for an additional drive, and that the computer's power supply is sufficiently powerful to handle the extra load.

The biggest issue is simply one of installation: you need to be comfortable opening up your machine and following the drive (or computer) manufacturer's instructions for installing the internal drive.

Or you may choose to have a technician do it for you.

Replace your Internal Drive

If you want that drive to be internal, but your computer doesn't have room for an additional internal drive (perhaps it's a laptop), or you just want your C: drive to remain as is, only bigger, the only practical alternative is to replace it. The complication here is that you'll need to move your data from one drive to the other as part of the replacement.

The typical sequence is to create a full system image backup, replace the hard drive, and then restore that image backup to the new drive. While that sounds simple, you'll need to make sure that your backup and restore software can handle restoring to a different sized drive, and that it has a way to restore to "bare metal", meaning a machine that has an empty hard drive with no operating system to boot into.

And once again, this scenario also requires that you be comfortable opening up your computer and fiddling around with the internals.

Bottom line: for most people unless you have special requirements an external drive is a fine solution. It's quick, easy and provides a much needed increase in capacity. The bonus is that you can move it to another computer just as quickly and easily as you installed it at first.

Article C3640 - February 6, 2009 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

February 6, 2009 1:58 PM

Another drawback (perhaps) to an external USB drive is you cannot copy very large files to them. On my system, I have a 160 GB external drive that is almost empty. I can copy 5GB one hour Tivo files to it but a two hour movie is 10GB+ and cannot be copied to the USB drive. Windows immediately responds with a drive full message in spite of there being plenty of space.

This may not be a USB drive issue. I do have reports, and have experienced myself, Windows choking on copying large files sometimes. You might try alternate ways of copying the file (Windows Explorer, or Copy or XCopy in the Windows Command Shell). I don't have a "this will fix it" for this secenario, but trying other approaches often helps.
- Leo

Rahul Mehta
February 6, 2009 5:08 PM

The purpose for increasing the capacity plays a major role in making this decision.

One advantage of an external drive is portability. If you are storing media files - pictures, music, video, you can take it along and connect to any computer to have these available there. Performance here is not of question as the media programs use buffering for replay.

For backups, the same advantage comes in to play if your main computer crashes. Your data is safely portable.

If your use will be to access the stored files frequently, internal drive has the advantage. Even in this case I would suggest is an external drive. With a little reorganization moving older less accessed files to the external drive.

My own strategy was to change the internal drive to a larger drive, go through fresh re-installation of the system and converting the older internal drive to an external drive for extra storage. I now have extra storage with better performance for my frequently used files on the PC and portable space for my backup files.

February 7, 2009 7:19 AM

There is another option that brings the two solutions together.
There is a case much similar in size to a DVD-R drive. You place it in one of the slots in your PC that are for placing DVD-R drives, screw it in place and connect the Drive cables to it.
The case has a drawer that can be locked in place when used, that comes out. All you have to do is place a regular internal hard drive in it, screw it in-place and slide the drawer back in. This allows changing disks simply, as often as you like and without having to open the case each time. The disk in the case is treated like an internal one, and is in fact connected as one in any important aspect.
However you still have to open the case and place hardware once. The flexibility however is great enough to make me think that the money paid to a technician to install the case that one time if you can't do it worth while.

Chris A
February 8, 2009 8:39 AM

Hey Ronny, is there any chance that your external is formatted in FAT32 and not NTFS? FAT32 will let you only transfer a maximum of 4GB at a time. You could always reformat the drive to NTFS and transfer any size file (well not any size, but you wont hit a max any time soon..) :)

February 10, 2009 9:40 AM

Also consider an external SATA drive (eSATA). These drives have similar performance to internal hard drives. There are eSATA drive bays that install directly into the computer that allow the swapping of drives but removing the problem of an extra box and cables. Here is an overview article on eSATA:

List of speeds for various interfaces from the article:

USB 1.1 15 Mbps
FireWire (1394a) 400 Mbps
USB 2.0 480 Mbps
FireWire 800 (1394b) 800 Mpbs
SATA 1.5 1.5 Gbps
SATA 3.0 3.0 Gbps

Older computers will require a SATA PCI card (and probably best use a USB or FireWire drive), but all newer computers have SATA native on the motherboard.

February 10, 2009 9:59 AM

For me, having an external jumbo hard drive was a blessing!I no longer need a jumbo hard drive for my OS since I use only 1 and do not partition. It just simplifies everything since I can "dump off" any "storable" information onto the external HD. This is what works best in MY situation and may not suite everyone's' needs or "tastes".

Corneliu Coterbic
February 10, 2009 10:30 AM

I have a 5oo GB Seagate external drive with all 3 interfaces, USB, FireWire 400 and eSATA. On USB I get 40 MBytes/sec transfer rate who seams to me OK.
My motherboard has an eSATA conection but it was very dificult for me to get a cable for it.

John Neeting
February 11, 2009 8:55 PM

My PC is an old 700mh running winXT. I have 12 drives configured as follows 2 internal, 4 drives off a plug in IDE expansion card - 2 primary,2 secondary buses which self configure and check at start up [ all run by a separate external PS ] and 6 usb drives from 2 usb2 ports to 2x4 port usb expansion boxes all PAP.
Speed for transfer e is not much of a problem since I have a mirror back up of everything [ data - programs ] I use Memeo-Auto sync to run in the back ground and take all the time it likes since it only copies something when I change a file on another drive. If a drive ever fails, Memeo copies it all back to the replaced drive, and I don't really care if it takes a few days to do it [ or over night ]. If I don't want Memeo to copy in the background, I just turn it off and do a normal copy - this too I can iconiz and carry on with other things. Because I turn off disk monitor, I never get a disk full sign. One thing to remember when using USB drives, if the drive hick-ups or suddenly stops for what ever reason, WinXP can stop too and leave you wondering whats happened while the system freezes. If this happens, unplug the USB drives first and if this is the problem, Windows will suddenly un-freeze [ and drop the drive letter in My computer ]. Western Digital tools and my book allows for PAP and pulling the cork WITHOUT stopping the drive normally [ Thank you WD :) ]

March 1, 2009 4:33 PM

I had similar problem than Ronny with an USB flash and may be it can be solved same way. The 2GB drive could copy only 400 MB of FILES in the drive and to further use it i needed to do it within a FOLDER in which the remaining capacity can be utilized.

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