I have a load of old external USB hard drives lying around - as I'm sure an increasing number of others do also.

Is there any way I can utilize these to act in some kind of RAID-type system?

Seems a waste to have all that storage lying around in uneven and relatively small chunks.

I'm using Windows Vista Ultimate 64 bit.

5 Answers 5


Been hunting around the net after the tip from KovBal about dynamic disks - and came across this thread.

Basically, RAID using external USB hard drives doesn't look too achievable.

One quote here.

Using USB as the transfer technology you're only going to achieve a 30-Megabyte or less transfer rate. You seem to be going to a lot of effort for a marginal result. For external use, eSATA is a much better choice for performance.

Maybe I don't understand the intent, but having 3 USB external drives working as a single "Dynamic" volume is almost certainly going to saturate the Hubs/Controller they are on.

And another quote here.

The overhead of software RAID will probably cause problems on USB drives. Even if you get it working I think it will probably be flaky and error prone. You can buy USB enclosures that you can install multiple drives in. These enclosures use an embedded Linux so that you can then setup a RAID array. This way the RAID calculations and read/writes are all done outside of Windows. The interface can be USB, SCSI, eSATA, LAN, whatever, it makes no difference. Software RAID is a compromise at best. I don't believe RAID 5 is supported in Vista in any case. I would look for a different way to achieve your goal.

  • Hey, I thought you wanted to see them as a single drive after you saw them "lying around in uneven and relatively small chunks." :)
    – KovBal
    Jul 20, 2009 at 14:28

This might be done with dynamic disks. I'm not sure if an USB hard drive can be converted to a dynamic disk, but this seems to be the only way to this. Once you converted your HDDs to dynamic disks you can create all kinds of RAID volumes. If your HDDs' sizes aren't equal, you can still use JBOD, so you can have them all in the same file system.

However, only Vista Enterprise and Ultimate supports dynamic disks.


I know Windows Home Server will aggregate all of your drives (including external) to look like one drive, I'm not sure if Vista can do it though...



Slightly related, I've seen someone RAID together iPod Shuffles, and it has some screenshots of how he did it on the Mac:


The process would be the same if you had many USB drives connected to your Mac.


The biggest downside with an actual RAID is that all the disks involved should be the same size or else it treats all other drives as the same size of the smallest drive. (eg. 2 x 20 GB drives and 1 x 100GB drive) will result in a 60 GB possible capacity - 3 x 20GB)

One of the advantages of ZFS (which has support in mostly server OSes, and not r/w on Windows and only read only by default on Mac OS X) is that you can mix and match drives and it shows them as one pool.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .