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USB Flash Drive RAIDers of Windows 7


It’s not especially easy to deploy, but Windows 7 supports simple software RAID. Here’s how to do it, using low-cost storage you already own: a bunch of USB flash drives. (I’d say I created a RAID array of USB drives simply to demonstrate the technique, but really… one reason to do this is because, well, I could. We techies can be so easily amused.)

There’s no such thing as enough disk room or a safe-enough hard drive. The moment you think you have enough hard disk space, you find yourself collecting high-definition videos or your hard disk starts whining and clicking. One solution to both problems is to use an ancient computing technique that dates back to when a big hard drive was 5 MBs and came in a casing as large as a washing machine: redundant arrays of inexpensive disks (RAID).

RAID has several benefits. The first is that RAID has the potential to deliver vastly increased data transfer rates. In theory, the input/output transmission rate of a RAID system can be more than ten times greater than a ordinary hard drive.

RAID pulls this trick off by “striping” data across the array’s disks. In English, this means that a file can be distributed across the array so that it can be read or written much more quickly. For example, With RAID, the system will place a file on the media so that while the first part of the file is being read from disk on one array, the second portion is already being picked up from disk two.

By enabling parallel data transfers, data throughput can be multiplied by the number of drives in the array. For example, a four disk RAID could have four times the throughput of an equal-sized single drive. A RAID that’s designed for speed and nothing but speed is called RAID Level 0.

The other major advantage of RAID is that you can mirror data from one drive to another, the most immediate form of backup one could imagine. Its disadvantage is that on RAID Level 1 you can use half a RAID’s maximum drive space for data storage. You also don’t gain the speed boost you get from RAID 0. Advanced versions of RAID let you retain more of the drive room while maintaining your data security. Unfortunately, in Windows 7, you can have one or the other, but you can’t have both.

Not for Most Users

You could, of course, buy a RAID hard drive controller or a full-scale storage area network (SAN) setup such as the Dell/EMC CX4-120. But, if all you need is to get more speed or more data security from existing Windows 7 PCs with multiple hard drives, why not use the tools that Microsoft has already put in the box?

If you opt for this path, you should keep in mind that this is not something you should trust even power users to do on their own. There are several ways to blow a RAID installation in Windows 7, and the worst of them will leave you with a drive that needs a visit to a repair shop, and possibly a user who needs therapy.

Also keep in mind that only Windows 7 Professional, Enterprise, and Ultimate support software RAID. If you’re going to try this, be sure that the PC doesn’t already support hardware RAID in its BIOS. If it does, you’re almost certainly better off using the built-in RAID since it’s very likely to provide much faster performance.

Setting Up RAID in Windows 7

With that in mind, let’s go over the basics. First, to set up a RAID using Windows 7?s built-in tools, you need to be logged in as the administrator. Your drives, or those portions you’ll be using for your RAID, must be the same size. In my case, I used a pair of inexpensive Best Buy 4GB USB Flash drives. A RAID of this size isn’t terribly useful, but I thought it would be interesting to use Flash drives in this way. Also, I couldn’t resist the temptation.

Once the drives (USB or otherwise) are installed and working properly, you’re going to end up blasting every last bit of data off them. That’s because normal, a.k.a. basic, drives with normal partition tables can’t be used in RAIDs. Instead, you need the drives to be set for dynamic storage. A “dynamic” disk can handle the spanned, striped, and mirrored volumes required for RAID. During this transformation, you delete the volumes on the drives and all the data therein.

To do this, head to Administrative Tools and Computer Management. Once there, under Storage, click on Disk Management. Pick the first drive for the RAID, and after making darn sure it’s the drive you really want, click on “Delete Volume.” Then pick out the next drive (you’re sure it’s that one, right?) repeat the “Delete Volume” until you’ve blasted all of them.

Then you move over to disk management to turn the drives into active disks and get rid of any pre-existing volumes.

If for some reason, this isn’t working for you, you can also accomplish the same thing from an enhanced command prompt; follow these instructions.

That destruction done, it’s time to create the RAID. Select the unallocated space in the first drive and right click on it. You are presented with four choices. You can skip the first one, simple (which, for all practical purposes treats as the drive as if were a basic drive). The next choice, New Spanned Volume, lets you treat multiple hard drives just as if they were one large drive. This technique, known by the name Just a bunch of disks (JBOD), can be useful at times, but since it’s not a RAID technology I won’t bother with it here.

The next choice, New Striped Volume, is where things gets interesting. If you elect to turn your drive (and its twin of course) into this kind of volume, you’ll end up with a RAID 0. In my informal testing, using my Mark 1 eyeball and PassMark PerformanceTest 7, I saw the average transfer rate increase by an average of 75%. Usually RAID 0 will produce a speed boost of about 100%, but I suspect what I was seeing was the result of an overworked USB controller rather than what you’d expect from Windows 7 RAID 0 with a more conventional setup.

Of course, the downside of creating an array of USB drives using RAID 0 was that my data wasn’t one bit more secure than it ever was. For better security, I needed the last available choice on the menu: New Mirrored Volume. With this, I created a RAID 1 drive. My two 4GB drives now gave me the equivalent of a single 4GB drive. In addition, my USB drives’ performance dropped by about 20%.

On the other hand, when I finally mangled the data of one of the USB drives — by repeatedly jerking one drive out of its socket with the fervor of a mischievous teething puppy let loose in a data center — I still had the data untouched and ready to go on its mirrored twin. As someone’s who dropped more than his fair share of laptops over the years, I can see how having an on-board mirror or an attached USB hard drive would be very useful at critical times.

Finally, I should note that during my week-plus of abusing and beating on these two generic USB drives to the tune of several thousand reads and writes, the drives held up remarkably well. While it’s commonplace to claim that a USB Flash drive can handle up to a million read and writes, I’m not sure I buy that. I am sure now, however, that even ordinary USB Flash drives, so long as they don’t end up in the washing machine, are likely to be good for years and years of ordinary use.

A version of this story was first published in IT Expert Voice.