How do I break a mirrored Raid in disc utility?

I have two 2.5 TB LaCie Biggest S2S external drives that I mirrored using Apple's Disc Utility. Now I would like to break the raid to free up Drive B without compromising the data on Drive A.
I have been told I could just unplug Drive A, erase and reformat Drive B, then plug Drive A back in... but would appreciate to hear from someone who has done this before and can confirm this is the right way to go about it.
Many thanks.

Thanks. I would do that, but when I click Delete, it gives me a warning that says:
Deleting a RAID set will destroy all information on the all the disks of the RAID set.
Are you sure you wish to delete the RAID set?
This makes me nervous, as I can't afford to have all information on both disks destroyed. Are you saying it won't destroy my data on both disks?

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How do i break the mirror ?

My root and var are mirrored , My server panic'd and i ran fsck on my filesystems but still cannot bring up this server how do i break the mirror ?

What are you using?
If it's DiskSuite then use metadetach, you will have to force this though. Also check your metadb's as you need 50% or more to be in a good state (this may be your problem).
#metadetach -f d* d# (* is the mirror name and # is the submirror slice)
#metadb
#metadb -d /dev/dsk/c*t*d*s* (to clear the metadb's on this disk)
To reinstate the metadb's you need to run:
#metadb -a -c <how many you want> /dev/dsk/c*t*d*s*
To reinstate the mirror it is:
#metattach d* d# (same numbers as above)
If Veritas just use option 5 of vxdiskadm.

How can I set up a RAID 1 disc set

How can I set up a RAID 1 disc set using my existing Time Machine backup disk plus another HDD without loosing my backup?
Thanks

TM is the worst, most cantankerous Backup App I've ever encountered... I'd pride myself if I could come up with a worse one!
Get carbon copy cloner to make an exact copy of your old HD to the New one...
http://www.bombich.com/software/ccc.html
Or SuperDuper...
http://www.shirt-pocket.com/SuperDuper/
Or the most expensive one & my favorite, Tri-Backup...
http://www.tri-edre.com/english/tribackup.html

"Create" button dim when attempting to setup mirrored RAID in Disk Utility.

I'm trying to setup a mirrored RAID in Disk Utility (v10.5.6) in MacOS 10.4.11 on a PowerMac G5. I've got the System and all of my files on a 500 GB Seagate internal drive and I've added a blank 500 GB Western Digital internal drive to be the mirror. When I boot from the Seagate drive and run Disk Utility, I can follow all of the instructions for setting up a mirrored RAID (except the last instruction):
1) Launch disk utility.
2) Select my boot drive.
3) Click on the RAID tab.
4) Enter a RAID Set Name and select a Volume Format (Mac OS Extended Journaled).
5) Drag a drive or volume to the set. Okay, I actually have a problem here, because if I drag the boot volume or drive to the set, nothing happens (it doesn't appear in the selection box). So I drag the blank volume to the set and it shows up in the selection box.
6) Select RAID type (RAID Slice).
7) Click the "Create" button.
That's the step that I can't complete; the "Create" button is dimmed (grayed out, disabled). My boot drive isn't partitioned (it has just one volume), I've run Disk Utility to repair Disk Permissions before I attempted to set up the RAID, and both drives are formatted as "Mac OS Extended Journaled." The only potential cause I can think of is that the two drives I'm using, though they're both 500 GB drives, are from different manufacturers. I can't imagine that would make a difference though.
Why is the "Create" button dimmed?
Any help would be GREATLY appreciated!
Thanks,
Scott

Hi there,
Thanks for your help!
Your explanation makes sense. I've just recovered from a hard drive failure and although I'd backed up most of the files the night before, I still lost a day's worth of email and several days worth of other files. Mirroring appealed to me because then I'd always have a completely up-to-date copy of everything, but your bad experiences with it give me pause.
Is there another backup strategy you can recommend that would give me really up-to-date backups of my entire boot volume?
Thanks again!
Scott

Rebuilding a Mirrored Raid using Disk Utility

I have a mirrored raid set up via disk utility. For some reason one drive was switched off recently so the 2 drives are now out of sync. Disk utility now says the raid is 'Degraded' with one of the slices marked as 'failed'
I can ignore this as the drive appears fine on the desktop. But I need it to be working correctly as a fully operating RAID.
If I click 'rebuild' it gives a warning saying 'Rebuilding a RAID set will destroy all information on the replacement disk “RAID Slice”.
SO- I'm assuming rebuild will correct the error and make it work but I'm concerned about this warning about destroying data! I assume it will simply copy everything from Drive A to the 'degraded' Drive B??
Thanks for any suggestions.

"SO- I'm assuming rebuild will correct the error and make it work but I'm concerned about this warning about destroying data! I assume it will simply copy everything from Drive A to the 'degraded' Drive B??"
This should indeed be the way it goes but since i do not have enough experience with that kind or RAID setup i strongly suggest backing up / cloning drive A to an external before doing the rebuild... just in case.

How so I break a raid mirror yet retain data?

I have 2 500g SATA drives on my Mac Pro3.1. They were set up by a friend as a raid mirror using the disc utility software. My question how can I break the raid "mirror" and use these harddrives as individual harddrives???
Thanks
Rich

From DU's Help:
*To delete a RAID set*:
Back up any important files.
In Disk Utility, select a disk in the set that you want to delete, and click RAID.
Select the RAID set.
If you’re deleting a mirrored RAID set and you see a Convert button, click it to convert the RAID set from version 1.0 to version 2.0.
Deleting a version 2.0 mirrored RAID set leaves a usable copy of the set’s files on each disk. Deleting a version 1.0 set leaves the disks unreadable.
Click Delete.

Mirrored RAID taking too long for Data Rebuild

I have created a RAID 1 (Mirrored RAID) using Disk Utility in my Mac Pro. I have used 2 x 4TB WD Enterprise Grade HDDs. I copied 10 gb data on to this 4 TB RAID volume. Then removed one of the HDDs & installed in my other Mac Pro. It mounted as normal HDD & showed all the data that I had copied. To check if Disk Utility will rebuild the data, I deleted some part of this data (2 GBs out of 10 GBs) & installed this drive back in the system on which I had Created this RAID volume.
Initially I was surprised to find that Deleted data is now absent on this RAID volume. But on Launching Disk Utility it started rebuilding data on RAID volume.
BUT for Rebuilding 2 GB data estimated time shown by system was 9 hrs.
Is this NORMAL?
I intend to fill this 4 TB RAID volume with approximately 3.5 TB Data. In case one of the drive fails, how long should it take for Disk Utility to rebuild this amount of Data?
Is there any alternative way of speeding up this process?
Will Apple's RAID card help?
All your suggestions will be appreciated.
Thanks

I know this is an old thread but I'd be interested in what you came up with for a solution.
Here's my RAID journey thus far.
https://discussions.apple.com/message/25119317#25119317
Again, a gig of info and its taking 1 day 10 hours.
I hope theres a solution somewhere.
Drew

What's the best way to upgrade a mirrored RAID drive?

I have two 3TB Firewire 800 drives which are almost full which I'd like to upgrade. The drives are configured as striped drives using the Apple (OS-X) RAID utility in disk utility. Is it possible to configure three drives as RAID 5, or four drives as RAID 10, or am I better off just going for a couple of larger drives and staying with the striped configuration? The drive is mainly used for an iTunes library, iMovie content and Aperture vaults so speed isn't that critical.
Thanks in advance

You can convert to a striped RAID but not without erasing the drives. The only ways to make a larger mirrored RAID are:
Buy two more identical drives. Make two sets of Striped RAIDs which in turn can be configured into one mirrored RAID by mirroring the two striped RAIDs.
Buy two larger drives, configure as a mirrored RAID, copy the data from the old RAID to the new one, or have two mirrored RAIDs.
Regardless of what you do you may end up erasing the data from the present setup if it involves breaking the RAID. If you break a mirrored RAID the data on each drive will remain intact until you re-use the drives in some other manner such as converting the mirrored RAID to a striped RAID.

Mirrored Raid as boot disk?

I have a flat panel iMac (PPC) that I would like to have a bit more reliable. Due to the number of files I have on this machine, it is currently configured to boot from an external Firewire drive. Recently, I have added a second external firewire drive of the same size, and am considering a Mirrored raid configuration for this system. I am primarily interested in reliability, not increasing the performance of the system, hence the mirrored, rather than stripped, raid configuration.
It is clear from other postings on the web that a stripped raid requires a) reformatting the drives, losing all data, and b) cannot be used as a boot drive, which is mandatory in this case.
Therefore my questions:
1) Can I create a mirrored RAID using Disk Utility without data loss? One drive is newly formatted, the other is full of data.
2) Can this RAID be used to boot an early flat panel iMac?

Hi Eric Hildum;
1) No.
2) Probably yes. Practically no because it is going to cause you more problems then it is worth running both disk ins a RAID over a single Firewire channel.
Don't forget that Raid is not a valid backup solution. Any data on the RAID array should also be backed up for it's protection.
Personally for the home user, I think a good backup solution beats RAID. Usually there are less problems with backup then RAID.
Allan

Concatenated Mirrored RAIDs

1) Can you take 4 equally sized (750GB in this case) hard drives, make 2 mirrored RAID arrays of 750GB each, then concatenate the two RAIDs using Apple's Disk Utility in OSX 10.4 Tiger?
2) Is this the best way to make a large 1.5TB, mirrored RAID using Disk Utility?
3) Also, if one of the drives fails, will I be able to remove it and just place another 750GB drive in it's place with no downtime? (Utilizing the RAID Mirror Autorebuild in Disk Utility)
Please help with these 3 questions. I'm supposed to set it all up 36 hours from this posting. (-;

It may help you to read this: http://en.wikipedia.org/wiki/RAID. Then read this: http://docs.info.apple.com/article.html?artnum=304377.

How to recover data from failed drive that's part of mirrored raid

Hi Guys,
hope to get help from someone knowledgeable out there. I have a macpro and recently experienced a failed drive. I set up that failed drive as part of a mirrored raid, this set is not my primary drive and so my computer is stilling up and running but now am wondering how I access the data from the mirrored drive. Should the mirrored drive automatically mount on my desktop whereby I would be able to access the files? This is my first drive failure and I was under the impression having a mirror would duplicate my data and allow me to access it in situations like this. I'm a bit of novice in this area and not sure if the data is truly on the "mirror" or if there are things I need to do.
I launched disk utility and was able to see the mirrored drive and I selected "mount" drive but it would not mount; I then selected "verify" and got "unrecognizeable filesystem" Is this normal? Am I suppose do something to get access to the mirrored drive? Do I install a new drive in place of the failed drive and expect the raid to rebuild automatically whereby I then see the data?
Your help is much appreciated.

Even with a mirror, you still need a backup.
Along with Disk Utility, you still need 3rd party (TechTool Pro 5, Disk Warrior 4.1.1+).
And if you like to use RAID and esp mirror RAID, consider
http://www.softraid.com which is a step above (the pdf guide, manual you can download and they have a demo, so worth the read). SoftRAID can also import/convert an Apple RAID to its own format which has been known to recover drives and data.

How do I add a new drive to a degraded MIRRORED RAID set?

My mirrored raid said it was degraded because one of the drives had a failure.
Today I unplugged the faulty drive and inserted a new one.
So far so good.
I erased the new drive.
Then I went into disk utility and followed the instructions in the help about RAID but I cannot see how to add this new drive to the RAID.
I'm confused.
1) The data is all on the RAID (the good, original slice) so can I add a new slice?
2) how do I do it?
Many thanks

I don't recommend the Apple hardware RAID card, and it doesn't work with off the shelf drives. If you are using drives in RAID, first make sure they are RAID Edition or lacking that Enterprise. Same make/model/firmware.
If using Seagate, avoid anything prior to 7200.12 series. If WD the RE2/3 series.
Rebuilds are slow, and one reason why I recommend 3 drives, even if you lose one you are covered still.
Of course just having two backups per volume is more important and comes first; mirrors are great for live editing and recording (audio) but otherwise... I'd stick to stripe and redundant backups. Only if you need 24/7. Otherwise, forget mirror.

How to separate drives in a mirrored RAID without losing contents?

Perhaps senseless questions (non-issues), I'm not sure. Better to ask than to regret a stupid move ...
I have an external mirrored RAID array (running 10.4.11) which is generally my startup volume(s) for a G4 Mini. Obviously, I can also boot from the internal drive.
1. What happens if I disconnect them from each other (firewire cable) ? Is the drive that remains connected to the CPU still accessible?
2. If I (somehow?) "Undo" the mirrored RAID set, is data on either or both drives lost or do the contents remain intact and accessible?
3. If drive contents remain intact and accessible, then how does one "undo" a RAID set" ? Disk Utility "Help" and several forum searches have not been helpful (void of all pertinent content).
My apologies if these are "stupid" questions and thanks in advance for informed responses.

thanks - nice to know
However - when I open DU, select this raid set, choose the RAID tab, I see NO option of "delete" - only "erase" button. Perhaps I need to (re)start from a different drive.
IMO neither one of those terms is exactly intuitive for uncoupling a mirrored set. I do not want to delete or erase anything, just uncouple them so they are once again independent drives (without loss of content). BTW, since I typically boot (start) from the current set, I presume that either drive (once decoupled) will also be boot-able with preferences etc. persevered!

Destroyed mirror RAID (1), Want to get data, but how?

I had a degraded mirrored RAID set that was functioning in its degraded state - reads and writes were no problem.
I thought that if I used DiskUtility to destroy the RAID, it would convert the drives to normal drives, and I would have access to each individually, but this was not the case. I also thought the data was backed up, but this was not the case.
I used the minus sign in the RAID tab DiskUtility to destroy the RAID. There are now 2 drives, but neither is able to be mounted:
bash-3.2# diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *698.6 Gi disk0
1: EFI 200.0 Mi disk0s1
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *698.6 Gi disk2
1: EFI 200.0 Mi disk2s1
2: Apple_HFS 698.3 Gi disk2s2
If I try to verify the first disk:
bash-3.2# diskutil verifyDisk disk0
Error encountered attempting to verify/repair disk0: Unrecognized filesystem (-9958)
but if I try to mount it, it thinks the mount is successful, but nothing new shows up on the Desktop, nor with "df"
bash-3.2# diskutil mountDisk disk0
Volume(s) mounted successfully
in reality, the drive is NOT "mounted successfully."
disk2 is in worse shape, as the OS is not even fooled into thinking it is mountable:
bash-3.2# diskutil mountDisk disk2
One or more volume(s) failed to mount
So I am trying to put my recovery efforts toward disk0.
Any ideas on how to mount the drive and get data off of it?

I had the same issue a few months back.
1 drive of my mirroed raid died. So I took the working drive out of that box and put it in a FW enclosure. It mounted fine. However after converting it back to a regular volume it would not mount. I tried everything thing I exhausted google searches.
the only fix was to reinitialise the drive. Luckily I had the data backed up elsewhere.

Mirrored RAID Set Questions

I initially set up a mirrored RAID set up on my system drive as a means of backing up my files. I've since decided I'd like to use Time Machine instead. When I try and break up the RAID set using Disk Utility, a lock icon appears next to the RAID set and I'm unable to "delete" the set. My guess is that I need to reboot off a different system, but since Lion didn't come with an install disc, and since Lion doesn't set up a Recovery HD on RAID sets, how would I go about unlinking this mirrored RAID set?
Conversely, I inadvertantly unlinked a different RAID set and would like to reconnect them, but Disk Utility says it'll erase all the data on the drives before it establishes the connection. Is there a way to reconnect a mirrored RAID set that has been disconnected?

For the first question, go back to the App Store download Lion again but before it begins the install stop the process and create a flash drive installer. See How to make a bootable Lion install disc or drive .
Remember you have to make sure the install process doesn;t proceed because once Lion is installed the installer app will be removed from your HD.
Sorry can;t help with the second question.
regards

How do I break a mirrored Raid in disc utility?

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