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RAID 0 with USB drives?

I'm trying to set up an external RAID 0 (mirrored) set using two LaCie 320GB external USB drives. No matter what I do in Disk Utility, it will not allow me to create the RAID set. I suspect the reason is I'm using USB drives, but I have not found any support or discussion to either confirm or disprove my suspicion.

The help is not really helping at all, it only says you need to use either SCSI or IDE disks -- well, I'm using the latter, but that's beside the point. Any suggestions are greatly appreciated.

Mac mini, Mac OS X (10.4.10)

Posted on Jul 30, 2007 3:23 PM

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9 replies

Jul 31, 2007 3:59 AM in response to JoHu

I have to say that I've never tried, or had reason to try, to set up a RAID based on USB-connected drives, but technically it's possible and a quick look at devices such as http://www.usbgear.com/computercabledetails.cfm?sku=USBG-RR2&cats=167&catid=167%2C131%2C161%2C312 suggests it can also be done in MacOS.

It may be that you are suffering an issue with the LaCie enclosures, or MacOS being unable to support this use with those devices, or -more likely I suspect- a problem caused by the drives both being accessed serially (on a single connector) rather than in parallel (via a discrete connector each).

Jul 31, 2007 6:27 AM in response to AndyO

Hi, thanks for your replies / comments. Alas, the drives are on separate connectors directly on the Mac mini. This is an Intel machine with four USBs. Still, maybe I should try switch the connectors around to see if that makes a difference. The drives are single disk only, so no reason for them to be RAID internally.

JoHu

Jul 31, 2007 6:45 AM in response to JoHu

Curious - technically this should work, though the issue with USB is that it doesn't differentiate between drives in the way that FW or SCSI does with their unique identifiers, or IDE does with master/slave designations. Thus if your drives are on the same USB bus, that could be the issue.

I wonder if you might get better assistance in the MacOS discussion areas? ( http://discussions.apple.com/category.jspa?categoryID=160)

Sorry, that's about the limit of my RAID 'expertise'!

Aug 14, 2007 1:32 PM in response to JoHu

I have also wondered about this very same question/concept. There are already devices out there that use raid such as, http://www.buffalotech.com/products/network-storage/terastation/ I have been thinking about getting one of these but I already have a few smaller drives that I would like to use. Well I guess the only way to find out if this works is to try it.

Aug 28, 2007 1:16 PM in response to AtrocityConnects

In Disk Utility go to "Partitioning", there choose "Options" and change the partitioning sheme of each disk you want to add to the RAID from "Master Boot Record" to Apple or GUID.

Explanation:
External FireWire/USB drives always come formatted with MS-DOS, Master Boot Record.
Soft RAID with Disk Utility does not support MS-DOS Master Boot record as partitioning method.
Even if you partitioned your HD's with "Apple HFS+ Journaled", this does not mean that the partitioning method was changed to Apple or GUID.

RAID 0 with USB drives?

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