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.
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).
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.
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 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.
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.
Thanks Dirk! That worked like a charm--I changed the partitioning scheme of each disk to "Apple" and re-partioned each with one giant partition and then dragged them over to create a nice fat mirrored RAID.