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Disk Utility's RAID feature doesn't seem to work System
I just wasted a couple of days trying to make Apple's Disk Utility RAID tool create a mirror of my Mac Mini's internal drive on an external FireWire drive. I finally gave up as the external partition was getting constantly corrupted (and the advertised "automatic rebuilding" didn't work).

I successfully used a mirrored RAID on an older G4 Tiger system with two internal drives, but according to the folks at SoftRAID, Apple's software RAID is basically intended for XServes and isn't even tested on external drives.

None of Disk Utility's help files give you any warning about this. In fact, in Snow Leopard, they don't accurately reflect the operation of the program: I saw a Demote button on the RAID setup panel that wasn't even mentioned in Help, and some of the RAID procedures described in Help simply didn't work.

I gave up on the RAID idea and instead have scheduled SuperDuper! to periodically make a Smart Update image copy of my boot drive to the external drive. Not quite as secure, but a lot less hassle! If you don't have an XServe and you really, really want a RAID, it appears that SoftRAID may be the best solution. It isn't cheap, though ($129 download).

[robg adds: If you've used Apple's RAID tool successfully on a recent Mac OS release, feel free to share your experiences. I've never tested it, so I can't confirm the above experiences.]
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Disk Utility's RAID feature doesn't seem to work
Authored by: SlaunchaMan on Oct 19, '09 07:40:56AM

I've used it recently with success. Instead of posting this complaint, why not submit a bug to Apple? Have you done so?



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Disk Utility's RAID feature doesn't seem to work
Authored by: valx on Oct 19, '09 07:44:43AM

I have created a few striped RAIDs with Disk Utility in 10.5. I've never had a problem with it. Works perfectly every time.



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Disk Utility's RAID feature doesn't seem to work
Authored by: mpanighetti on Oct 19, '09 07:49:28AM

I've got a perfectly functional striped RAID of a dual bay enclosure over USB created in Snow Leopard. It's running my iTunes library, and I haven't had any issues.

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Thanks a million. Push Start to replay.



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Disk Utility's RAID feature doesn't seem to work
Authored by: ThreeTwo on Oct 19, '09 08:05:58AM

Works fine on 10.6.1, RAID 0 on 4 internal Intel SSD 160GB generation two, many weeks now. Running heavy loads, too, multiple VMware machines, Logic Pro with multiple third-party disk-streaming virtual instruments, etc. SoftRaid is selling a product -- which works very well and I use it elsewhere, but nonetheless you are reading an advertisement.



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Disk Utility's RAID feature doesn't seem to work
Authored by: folotp on Oct 19, '09 08:13:50AM

Hi,

I have sucessfully used both stripped and mirrored Software RAID sets on external hard drives (both USB and Firewire, even mixed), in both Mac OS X 10.5 and 10.6.

However, booting off of a Software RAID is not supported. From your post, it seems that this is what you are trying to do by mirroring your internal hard drive...



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Disk Utility's RAID feature doesn't seem to work
Authored by: pdm on Oct 19, '09 08:34:20AM
> However, booting off of a Software RAID is not supported. From your post, it seems that this is what you are trying to do by mirroring your internal hard drive.

This isn't true. In my Mac Pro I am using software RAID 1+0 and boot from this with no problems at all.

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-pdm


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Disk Utility's RAID feature doesn't seem to work
Authored by: gylgamesh5 on Oct 20, '09 09:36:04AM
Incorrect. RAID booting is supported on some Macs (your Mac), but not all Macs.

Intel-based Macs: Flashing question mark when trying to boot from RAID volume
  • Last Modified: November 09, 2006
  • Article: TA24104
  • Old Article: 303692
Products Affected

Mac mini (Mid 2007), Mac mini (Late 2006), Mac mini (Early 2006), iMac (20-inch, Mid 2007), iMac (24-inch Mid 2007), iMac (Mid 2006 17-inch), iMac (Early 2006 20-inch), iMac (Early 2006 17-inch), iMac (24-inch, Late 2006), MacBook Pro, Mac mini, iMac (20-inch Late 2006), iMac (17-inch, Late 2006 CD), iMac (17-inch, Late 2006), iMac (24-inch, Early 2008), iMac (20-inch, Early 2008)

Some Intel-based Macs do not support booting from software RAID volumes. If you try to start these Intel-based Macs up from a software RAID volume, the computer may start up to a flashing question mark.

The following computers do not support booting from software RAID volumes:

  • MacBook
  • MacBook Pro (not including MacBook Pro (Core 2 Duo) models)
  • iMac (Early 2006)
  • Mac mini (Early 2006)

This document will be updated as more information becomes available.

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"To die among friends. Can a man ask for more? Can the world offer less? Who wants to live till the last bottle's empty? It's all for


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Disk Utility's RAID feature doesn't seem to work
Authored by: babbage on Oct 20, '09 11:59:16AM

Oddly enough, the list of unsupported computers happens to be identical to the list of computers that don't include a spare SATA bay to install a second drive to create a RAID set with.

You could remove the optical drive, sure, but that's exactly the sort of thing that Apple isn't likely to condone within the context of a valid warranty.

As far as I can tell, software RAID works just fine on any Mac that has room for at least a pair of SATA drives. My G5 tower at home has been running from a mirrored pair of 1.5TB drives for months now without a problem.

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DO NOT LEAVE IT IS NOT REAL



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Disk Utility's RAID feature doesn't seem to work
Authored by: Beorn on Oct 19, '09 08:18:22AM
I have also had success with several software RAID configurations out of Disk Utility. Up until my recent Drobo purchase, I was mirroring my two 500GB FW800 LaCie drives in this manner and had absolutely no issues. In fact, one of my drives did die, and the RAID rebuilt itself automatically after LaCie shipped me the replacement. I agree that this is not a hint, and if true may possibly be an indication of faulty hardware (or software?) on the OP's machine.

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Disk Utility's RAID feature doesn't seem to work
Authored by: nvdingo on Oct 19, '09 08:38:06AM

Consider what you are trying to accomplish here...
You are trying to create a stripe with your existing boot drive and an external firewire drive.
the boot drive needs to be ready immediately for boot, while the firewire drivers aren't loaded til later. This causes a timing issue in availability of the drives for the RAID. As others have said, i wouldn't ever really want to boot from a software raid for data safety.
Creating a RAID of 2 internal drives or 2 external drives should work fine. Just for the hell of it i created a striped array of 7 usb flash drives plugged into one hub to see if it worked. it did.
In general, to make sure all drives are ready at the time the RAID is to be recreated by the drivers, try to keep all drives at least on the same interface type.



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Disk Utility's RAID feature doesn't seem to work
Authored by: jmz on Oct 19, '09 10:30:53AM

I second that



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Disk Utility's RAID feature doesn't seem to work
Authored by: diamondsw on Oct 19, '09 08:40:22AM
Works just fine on my Mac Mini with an external Firewire array. Sounds very likely your disks are bad to begin with.

Also, if SuperDuper is a solution to your problems in any way, then you don't need RAID in the first place. RAID is not backup, and should never be used as such. It is for high availability to protect against hardware failure. Any sort of software error or corruption will immediately destroy both disks.

If SuperDuper is getting the job done, then the job is backup, not high availability.

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Disk Utility's RAID feature doesn't seem to work
Authored by: NinjaRat on Oct 19, '09 09:03:40AM

The fault here is not with Apple's software RAID system -- which is based on the FreeBSD software RAID system and is intended for a lot more than just XServe, because XServe uses hardware RAID controllers. The SoftRAID people are lying to you in order to get you to buy their products. The fault is that you are trying to mirror the internal boot drive to an external volume. Non-homogenous mirroring is never a good idea. In your configuration you would be much better off using the external drive as either a Time Machine or CCC/SD backup.

For the record, I use a pair of 500GB Firewire 400/800 drives from Seagate with Apple's software RAID with both a G4 Mac Mini running 10.5 and a MacBook Pro with 10.5 and recently 10.6. They've been working perfectly fine like this for over 3 years and yes, I do swap the RAID between the two on a frequent basis.



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Disk Utility's RAID feature doesn't seem to work
Authored by: MalEbenSo on Oct 19, '09 09:42:50AM

My scenario has been different. But at the end of the day I, too, found Disk Utilities RAID functionality too problematic to use.

I have used two Seagate FreeAgent Pro disks via FW in a RAID 1. The problems I faced were that
a) the RAID would break (for whatever reason, I could not reproduce, but it happened ca 3-4 times in ca. one year)
b) it actually broke without warning before mounting the single disk: no error message
c) it continued to operate without warning that it is running one disk alone: e. g. no changed icon in the finder
d) Disk utility took very long to restore the RAID, ca. one day for 1 TB, whereas typical transfer rates to either drive and the RAID were much higher. Needless to say that I left the Mac and drives alone while restoring.

I finally decided to break the mirror and use two separate disks and a different backup strategy. Alas, another problem arose:
e) Breaking the mirror via Disk Utility left the two disks with the same device id (UUID), which caused all sorts of problems when the two disks were mounted simultaneously.

So the best I can say re. b) and c) is that the mirror worked in that upon "failure" of one drive the RAID continued to function. Too bad that the drive didn't really fail.

And yes, I have filed bugs for Apple.



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Disk Utility's RAID feature doesn't seem to work
Authored by: Alrescha on Oct 19, '09 10:08:54AM

I have a pair of external drives striped together as a Time Machine volume.

At work, I have a pair of internal drives striped together as the boot volume, and another pair as a Time Machine volume.

All this has worked fine in both Leopard and Snow Leopard.

A.



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Disk Utility's RAID feature doesn't seem to work
Authored by: MacLane on Oct 19, '09 10:22:03AM

I used it with good results. I set up 2 pairs both striped (RAID 0) on a Mac Pro. I got roughly 2 to 3 times faster copies and duplications. I tried RAID 10 but the speeds were reduced too much - - down to what you'd expect from a single drive. I also tried mirroring (RAID 1) by itself, but while someone had commented that it did not slow his throughput by a significant amount, it did slow mine down too much (maybe 30%--I didn't make note of any of my figures as I didn't expect to be conveying them to others) to put up with on my 2 x 2.66 Dual-Core Xeon. To sum up, copying and startup is much faster, but the computer does not otherwise seem any zippier with the applications I use.



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Disk Utility's RAID feature doesn't seem to work
Authored by: robogobo on Oct 19, '09 10:26:18AM

I have a (successful) striped RAID on two internal drives in my Mac Pro, created in Leopard and working fine in SL. RAID isn't a very efficient backup strategy, and really should only be used to improve read/write performance or for redundancy to eliminate downtime in case of failure. It's better for you and your machine to backup with a cloning utility, always and anyway.



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Disk Utility's RAID feature doesn't seem to work
Authored by: jmz on Oct 19, '09 10:30:09AM

I've been using the RAID possibilitiy for years without a problem. There are about 20 Mac mini/Mac Pros as servers at customers of mine and all are using the raid option. Always RAID 1 with 2 internal and on the mini even with 2 external FireWire drives. No problems and the automatic rebuild works in two cases.



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Disk Utility's RAID feature doesn't seem to work
Authored by: M-3 on Oct 19, '09 12:10:39PM

I don't know why in God's name you would try to make a RAID of two entirely different disks on two entirely different busses in two entirely different enclosures but for every reason I just listed (and more) it shouldn't even be attempted. If you want a mirror of your internal drive on an external 1394 drive, just use Time Machine.



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Disk Utility's RAID feature doesn't seem to work
Authored by: Zeitkind on Oct 19, '09 05:01:00PM

I agree that the Apple RAID tools are horrific to use and a lot of bugs still wait to get fixed - if ever. But it does work with external drives, though it's a good idea to use drives connected the same way, i.e. only external Firewire drives oder only internal SATA/PATA drives. Mixing them is a no-no! for any RAID's, not only for software based solutions.
If at all, I always use the shell commands to create, fix or delete RAID's in OS X, the tools are more reliable from what I learned over the years. And if possible, by ssh'ing into a machine with no users loged in.



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OS X RAID hints
Authored by: gabester on Oct 19, '09 07:34:07PM
Use the same bus.
Use the same enclosure type.
Use the same make and model of drive.
Use the command-line for configuration.
Always make sure ALL drives in the RAID set are powered on before connecting them to the bus and mounting them in the OS.

Follow these steps and your RAID will work. I once forgot to power both drives on and needless to say the RAID was then degraded because as the OS booted it attempted to load the RAID and only one disk was available. Rebuilding it (a pair of 500GB IDE drives in FireWire enclosures connected to a Mac mini's FW400 port) took about 12 hours.

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Disk Utility's RAID feature doesn't seem to work
Authored by: nickv2002 on Oct 20, '09 01:00:33PM

I have a RAID 0 (Mirror) of my iTunes library on 2 extra drives in my Mac Pro that's worked in 10.4. 10.5, and now 10.6 without any problems. I've never tried RAIDing external drives though.



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Disk Utility's RAID feature doesn't seem to work
Authored by: MarioGardenghi on Oct 21, '09 05:49:55AM

Using RAID 0 on a MacPro 2009 with 2 Velociraptor SATA disks for months without any problems.

I had problems in the early days since one disk had bad sectors and the raid went crazy.

The solution? When you create a RAID make sure to always low-level format the disks before creating the raid set.



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works here with matched busses
Authored by: saint.duo on Oct 22, '09 01:58:42AM

I have 2x 250GB drives inside of a single firewire enclosure in Raid 1, and have been using it like this for over a year now without any corruption or issues. I also have 2 1TB drives inside of a PowerMac G5 running OS X server in a Raid 1, again no issues. Both are using Apple's software raid.

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duo



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