Possible to do RAID 5 via 3 identical, external USB drives?

Is it possible to create, under Windows XP Pro, a RAID 5 (or at least RAID 1 [mirror]) array by using 3 identical, designed-for-RAID-by-Western-Digital, internal hard drives that are each mounted in their own (non-identical) SATA-to-USB enclosure?  Is there a hub-type device that can be used to accomplish this task?

If so, then I can move my array from PC to PC, as I wish, which will be frequently.

Thanks.  I'll be impressed if somebody can come up with a way for me to do this.  I've never seen such a device.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
There is no supported way on XP to do this.  It is TECHNICALLY possible to do it on Server operating systems, but in either case, this is a HORRIBLE idea.  Performance would be awful and you would have a SERIOUSLY increased risk of data corruption.
Rob WilliamsCommented:
Seems to me Windows 7 will support raid 1 with USB drives, but not raid 5, and XP and vista definitely do not offer the capability. As Leew pointed out there are serious risks of corruption though (with Win7). You cannot remove the USB drive.

You can buy network attached storage devises that connect to the network, rather than USB, house multiple drives, and offer RAID within the box itself. Netgear has one that offers RAID 1 for about $150 + the cost of the drives. It works well but there are dozens of others.
Rob WilliamsCommented:
Just as an example, most of the following offer external RAID 5 storage. RAID 1 is quite a bit less:
I would ditch USB totally, and opt for eSATA which is 3 times faster.

Calvary and others have RAID 1 and RAID 5 options in external eSATA boxes.

I hope this helps !
mrmoderateAuthor Commented:
Is it technically possible to design the system I originally asked about?  Could the potential data corruption problem, in theory, be fixed, perhaps at the expense of speed?

I should make clearer my original question.  If you are somebody who has accumulated a bunch of WD RAID-oriented, identical drives, but you have 3 different cases, each of which turns the identical, internal drive into an external USB drive, is it possible to plug each of these drives into a single Windows XP Pro machine and make Windows treat the three drives as, ideally a RAID 5 array, but at least a RAID 1 (mirrored) array.   Is there no hardware or software way to do this?

Can it be done, in practice?

Can it be done, in theory?
Lee W, MVPTechnology and Business Process AdvisorCommented:
As I said, there is no supported way in XP to make a software RAID array (other than RAID 0).  I know this will work with server - I inadvertantly mixed a USB drive with other drives attached via IDE on a server I was working on and the RAID picked right up where it left off (it was a software RAID on the IDE controllers, we added a hardware RAID controller and new drives to replace the software RAID controller - I put the old drives back in to recover data faster than backup and was just expecting a degraded RAID but forgot I had the third drive connected via USB because it had some non-RAID partitions as well...

I cannot think of any company who would create a USB Hardware RAID device that did not create the RAID internally using it's own disks - no point to use a USB hub-like device that would create a RAID.  

The main problem with the USB solution is simply that there's no way the USB controller is designed to handle something like a RAID 5 configuration; there are too many variables.

It's possible to implement software RAID with external drives if you use eSATA or Firewire, either of which has advantages over USB in that you're less likely to be sharing the bus with keyboards, mice, pen drives etc.

I can't see how you'd be able to take the array off one machine and share it with another unless you had a hardware RAID controller on the external bus and connected the drives to that.
Rob WilliamsCommented:
I will re-iterate as well, XP has no RAID functionality.

What do you mean by "RAID-oriented"? Are these external SCSI drives, SATA, or what? You could by a SCSI/SATA hardware raid controller, put them in one physical box, configure RAID, and install any O/S on the RAID array, assuming the drivers exists.
mrmoderateAuthor Commented:
Um, RobWill:

XP or motherboards that run XP nicely will let you plug in two identical drives, and it will treat them as a RAID 0 or 1 array, if you set it up that way, I believe in Disk Management.

By "RAID-oriented" I mean that I was warned on other threads or articles that a problem with RAID is that there will be something like a small delay in writing to one of the drives, for whatever reason, and the RAID controller will immediately conclude that the drive has been compromised.  The controller will then immediately begin trying to rebuild that entire drive's data, or it will stop writing to that drive.  Or something like that.  Some drives, such as (some of?) those that Western Digital tout as "Enterprise," have some sort of setting that prevents that from happening.

Any further comments or advice, anybody?

Thanks for the comments I've gotten so far.
Rob WilliamsCommented:
"You cannot create mirrored [Raid 1] volumes or RAID-5 volumes on Windows XP Home Edition, Windows XP Professional, or Windows XP 64-Bit Edition-based computers."
from: http://support.microsoft.com/kb/314343
I believe XP does support stripped volumes.

However there are many motherboards, especially "entry level server boards" (glorified desktop boards) that have a built-in raid controller to create a raid 0 or 1 array (stripped or mirrored), within the BIOS itself. You install the drivers for this with the F6 key during the XP install, and XP sees it as a single drive. However, one feature I do not like with these mirrors is the only way you know if the mirror fails is a brief "degraded" message at boot. There is no warning within XP such as the event logs. A few do offer monitoring software.
mrmoderateAuthor Commented:

I'm tempted to give you all the points for this question.  I won't, because I thank you all, in varying degrees, for the education you've provided me.


Again, thanks all.
Rob is saying that you can not do a software RAID at the OS level, you need ot have the RAID done in hardware on the motherboard or using a new RAID controller added to your motherboard, or as I suggested, a RAID 1 in an external box.

I hope this helps !
Rob WilliamsCommented:
Not sure what you would like to know. Please advise if we can provide more details.
The Dell XPS does not natively support Mirroring, it does support stripping (Raid 0), as per the following article.

If you want to create a raid 1 array (mirror) with that PC you would have to add a Raid controller as stated by SysExpert.
mrmoderateAuthor Commented:

You said, "...one feature I do not like with these mirrors [meaning RAID 1 setups controlled by the PC's
 BIOS] is the only way you know if the mirror fails is a brief 'degraded' message at boot. There is no warning within XP such as the event logs. A few do offer monitoring software."

Sounds like a good solution to me, so long as the monitoring software is both good and cheap.

To all:

Why would somebody want to create a RAID array out of a bunch of non-identical, external, USB hard drives?  Because there are tons of these drives around.  The price of the drives will fall, and so you'll be able to pick them up, on eBay for example, for dirt cheap.  Wouldn't it be nice to have a gizmo with a bunch of USB connectors, and this gizmo allows you to add instant (more or less) storage space whenever you choose?

Incidentally, just because the device I envision looks more or less like a USB hub, does not mean that it's circuitry need resemble a USB hub at all.

Can this be done, in theory?

Thanks to everybody for your replies.
Rob WilliamsCommented:
The monitoring software is free. It is available from the motherboard manufacturer, but it is only available for a few motherboards.
Using the motherboard's raid controller only works with IDE and SATA drives, it will not work with USB drives.

Using USB drives, if it would work, is extremely risky as the minute you disconnect a USB drive you have broken the mirror and it has to be rebuilt.

Also picking up a bunch of dis-similar drives on e-bay is not a recommended practice for any raid configuration. Raid arrays should be built with matching drives so that write speeds and other parameters are identical. If not corruption and/or RAID failure can occur.

Basically we are telling you there is no cheap simple solutions. If you want a basic RAID 1 mirror, you should buy a motherboard that supports it and two internal matching drives, or buy a server operating system and again internal matching drives.
You asked:  "Is it possible to create, under Windows XP Pro, a RAID 5 (or at least RAID 1 [mirror]) array by using 3 identical, designed-for-RAID-by-Western-Digital, internal hard drives that are each mounted in their own (non-identical) SATA-to-USB enclosure?  Is there a hub-type device that can be used to accomplish this task?  If so, then I can move my array from PC to PC, as I wish, which will be frequently."

Short answer is Yes you can, no there isn't, and yes you can but it's a manual process.  Long answers are below...

Yes it can be done.  You need external USB hard drives and the SATA-to-USB enclosures need to show the drive as a hard drive, not removables (like memory sticks).

Initialize the external USB drives into dynamic disks.  Then make a RAID5 volume across the dynamic disks (make three drives into dynamic disks, make volume, set RAID5 and select the three drives and set the size of the volume).  This can be done an XP Pro (not sure of XP Home).

You can do XP software RAID across any dynamic disk (internal or external, it doesn't matter), and you can only make hard drives (not removables) into dynamic drives.

No there isn't a "special" hub or device, all you need is enough USB ports to plug in all the drives or a USB hub if you don't have enough ports on the computer.

As for moving between machines, you will need to import foreign disk after you plug in all the drives in the set into the new machine.  There's a signature on the dynamic disk that indicates which Windows host owns the volume, that's why it shows up as a "foreign disk" when you present a dynamic disk to a different computer.  Also when you import the foreign disk, it needs all disks that's part of the volume set.  So if you plug in two out of three of a RAID5 set, the import will work (you'll see the volumes) but they won't be mountable until all required volumes are present.

And there IS and easier way.  Get a multi-bay external RAID enclosure (http://www.nextag.com/raid-enclosure-4-bay/compare-html).  This shows up as a single external drive even though it may be a RAID5 LUN so you won't have to import foreign disk.  Little more expensive, but less parts to carry around between machines and no importing foreign disks.

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Rob WilliamsCommented:
I think you will find XP pro only supports spanned or striped (Raid 0) volumes, and not Mirrored (Raid 1), or Raid 5 configurations.
also, until USB 3.0 comes out, eSATA is at least 3 times faster.

Rob WilliamsCommented:
External drives connected by USB, a hacked O/S, and no support. That would be a fault tolerant system ;-)

For the record VXDguy, EE does not condone hacks or O/S license violations.
I just did the request attention link and asked EE to remove the URL in the comment.  I wouldn't want to contribue to the deliquency of an EE customer :)
andyalderSaggar maker's framemakerCommented:
I reported that hack/link to Microsoft several months ago and they haven't had it taken down. I guess they're not too concerned since it's only home PCs that it's going to be done on and a servicepack could even update the file and kill the array permanently. Perhaps I should have reported it to Symantec since it's Veritas' technology that it's using.
mrmoderateAuthor Commented:
Uh, I kinda lost you guys at the end, there, but it's been a really interesting discussion.  I think I'll award points now.  Thanks to all.
Rob WilliamsCommented:
Thanks mrmoderate.
Cheers !
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