Possibly boneheaded question re mirrored raid

Hi, if half of a mirrored raid set up with disk utility fails does the volume stay mounted and usable? Or is there still some sort of recovery necessary?
I'm thinking yes that's the point but I thought I'd better ask.
Thanks,
Dave

Both drives should be on independent bus or using a controller. The MDD has two buses, but ATA/66 and ATA/100 differ by 4% and enough difference to not recommend using two drives in any form of stripped or mirrored RAID.
Two drives on same bus, master/slave I would avoid as the bus has to wait for one drive for I/O before it can talk to the second drive.
With an SATA no such problem or limitation, or using an ATA controller with two independent channels.

Similar Messages

Possible to convert a mirrored RAID boot drive to a single disc boot drive

hi ... i made the mistake of installing my Macpro with a RAID on the first two drive bays as a startup disc. Although this doesn't pose any problems per se i would like to have a single disc startup drive now but i do not have the time or courage to re-install and re-configure everything (installation&config with all software takes 3 days due to the huge number of software i have on this machine).
is it possible (and how) to get rid of the RAID and convert one of the discs to a normal startup volume so i can reformat the second disc and use it as a work drive ? Since the 'mirrored' drives both contaion a full startup drive this should be possible i think but could not find any info on this.
thx for any help with this ...

hey .. funny how expert opinions vary ... i have a handfull of IT and software RAID experts who disagree with you ... in my case, i'd rather get rid of it ... ( however i still have to find a solution to clone my boot drive that works flawlessly with all my software ... )
anyways ... how exactly do i go about splitting the RAID, to make sure i don't mess it up ....
1. restart from CD
2. Delete the mirrored RAID set
3. remove one of the HDs with the raid slice on it (i'll keep it as a backup 4 the moment just in case)
4. restart from the remaining slice disc
5. ... ?
do i need to do anything specific ... ? what about the name of the Volume .. for the moment my startup disk (the RAID) is called 'BootRAID' ... the slices are called 'RAID Slice (disk0s2)' and 'RAID Slice (disk1s2)' .. in order for everything to work properly, don't i have to rename the new startup disk ?
i'm scared ...
here's a screenshot of my setup: http://kinkajou.net/diskUtility_RAID.jpg
<Edited by Moderator>

Mirrored RAID Question

Possibly a dumb question: If Mac OSX (10.4.11 in this case) boots from a mirrored RAID (2 drives), is there any additional protection from routine disk directory errors? Again, I'm not asking about the physical failure of one of the drives, but from the type of directory errors that sometimes happen after a system freeze or loss of AC power to the system.
Another way of asking the same question: Will disk directory errors in one drive be automatically mirrored in the second drive, or will the second drive not have the same directory errors?
Background: I've got an older G4 tower with two identical drives installed that I use as a play/experiment computer. I can either keep the two drives totally independent and do daily (or even more often) total, bootable backups from the primary to the backup drive, or else configure as a mirrored RAID.
Thanks.

Both drives should be on independent bus or using a controller. The MDD has two buses, but ATA/66 and ATA/100 differ by 4% and enough difference to not recommend using two drives in any form of stripped or mirrored RAID.
Two drives on same bus, master/slave I would avoid as the bus has to wait for one drive for I/O before it can talk to the second drive.
With an SATA no such problem or limitation, or using an ATA controller with two independent channels.

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

Possible to boot B&W G3 from mirrored RAID??

Hi all,
I've tried to get my B&W, running server 10.3.9, to boot from a mirrored RAID (RAID 1). So far, I can successfully create the RAID, run the software installer, and choose the RAID with Startup Disk, but upon restart, it doesn't recognize a valid system (flashing system folder/question mark).
There's a tech article that states the B&W G3 won't boot from a striped RAID (RAID 0), but I've not been able to find anything definitive regarding mirrored RAID. Does anyone know for sure (or know where I can find documentation)?
TIA,
Brad
B&W G3 Mac OS X (10.3.9) 10.3.9 server

Thanks for the info. I had no problem either creating the RAID (successfully in both Disk Utility and Terminal), installing the OS, or selecting the RAID pair as the startup disk. I'm doing this with ATA disks.
Once done, though, the system won't boot from the RAID pair. I know that the B&W open firmware won't allow startup from striped RAID (technical article http://docs.info.apple.com/article.html?artnum=58258 applies), but don't know if this applies to mirrored RAID as well.
Has anyone out there successfully booted a B&W G3 from a RAID 1 configuration?

Little software mirror raid configuration question

Setting up a Boot volume mirror RAID of two internal drives with Disk Utility -- any suggestions as to whether to check "RAID Mirror AutoRebuild" or not?
I understand the concept, but in practice am wondering, if I leave it unchecked, will I be notified if one of the drives fails? Don't really want to be having to manually check periodically if both are still running okay...
Thanks!

Thanks so much for thoughts and that great software pointer. I bought two of the same make/model drives with this mirror in mind so I should be cool there.
Yeah, I know your backup advice is very sound -- and I'm absolutely still chewing on whether I want to put my eggs in Mirror RAID or Super Duper. I understand the pro/cons of each, but I also just know that I'm not going to do both -- I'm just not that high maintenance/big spender.
I was edging towards mirror just because, in 3 years of doing regular clone backups I've never happened to have the need to restore yesterday's system due to a bum software update or the like, but I have had drives fail on me and lose the last two days of intensive work... I like that with Mirror there's no thought.

Recovering data from a damaged mirrored RAID

I have a puzzle I'm hoping you can help me with: I have a mirrored RAID array in a MD G4 which is not mounting (since going to Apple for replacing the logic board).
I have tried connecting both drives to a Forensic FireWire dock to no avail; they show up as "spare" and not as a "slice".
Any suggestions?
Yours truly,
-Tom
FYI - Below are the results of "diskutil checkRAID" and "diskutil list" on this G4:
#diskutil checkRAID
RAID SETS
Name: Stuff
Unique ID: 58607662-4550-11D8-84ED-000393D28706
Type: Mirror
Status: Offline
Device Node: disk4
Apple RAID Version: 1
# Device Node UUID Status
1 disk1s4 AF8C5D0C-24F3-4EA3-A123-5F5E22FA6D65 Spare
0 disk2s3 027E86C9-88CE-4973-9984-C7A010C422FF Spare
2 Unknown Missing/Damaged
2 Unknown Missing/Damaged
#diskutil list
/dev/disk0
#: type name size identifier
0: Applepartitionscheme *114.5 GB disk0
1: Applepartitionmap 31.5 KB disk0s1
2: Apple_HFS Backup 114.5 GB disk0s2
/dev/disk1
#: type name size identifier
0: Applepartitionscheme *149.1 GB disk1
1: Applepartitionmap 31.5 KB disk1s1
2: Apple_Boot 128.0 MB disk1s3
3: Apple_RAID 148.9 GB disk1s4
/dev/disk2
#: type name size identifier
0: Applepartitionscheme *149.1 GB disk2
1: Applepartitionmap 31.5 KB disk2s1
2: AppleDriverOpenFirmware 512.0 KB disk2s2
3: AppleBootRAID 149.1 GB disk2s3
/dev/disk3
#: type name size identifier
0: Applepartitionscheme *74.5 GB disk3
1: Applepartitionmap 31.5 KB disk3s1
2: Apple_Driver43 28.0 KB disk3s2
3: Apple_Driver43 28.0 KB disk3s3
4: AppleDriverATA 28.0 KB disk3s4
5: AppleDriverATA 28.0 KB disk3s5
6: Apple_FWDriver 256.0 KB disk3s6
7: AppleDriverIOKit 256.0 KB disk3s7
8: Apple_Patches 256.0 KB disk3s8
9: Apple_HFS Laura 74.5 GB disk3s9
/dev/disk4
#: type name size identifier
0: *0.0 B disk4

Razorlance wrote:
Is it possible to just put the old SSD in the new laptop then?
Maybe, I just cannot say with authority. Even if they were physically the same, the question is what OSX is on the older SSD. If it is older than the one the new MBP came with, it will not work.
Ciao.

Mirro Raid can you use a single 4TB disk with 2 partitions for mirrored raid ?

Hello,
I have a new 4TB hardrive.
After lots of reading, i was thinking that i could partician the drive to 2 (2TB) Then create mirror raid.
Essentially thinking that i would have photos on one of the (2TB particions) and they would mirror on the other ?? as a double copy storage.
I can partician okay and the try to drag the two particians onto the "mirror raid set" and ithe following message displays :
"Can't add Seagate expansion disk" to the raid set because another volume from this disk is already part of the RAID set"
I'm now thinking i need to purchase another 4tb hardrive for this to work ?
Or if you "mirror raid set" is it actually particioning the drive and creating a copy ?
Forgive me... i'm not really very up skilled with disk utility, and basically just don't understand.
Looking forward to some help and advise
warm regards Tracy Gr

It doesn't make any sense to mirror on the same drive. The idea behind mirroring is that should one disk in the raid set fail your data is safe on the other disk. Mirroring to partitions, if it's even possible, would only bring you disaster when the drive fails because you would lose the complete raid set and all of your data. If you insist on mirroring buy another drive.

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

Re-create a mirrored RAID after restoring backup

As a follow-up on my thread http://discussions.apple.com/thread.jspa?threadID=833779&tstart=0 :
On a XServe G5 with OS X Server 10.4.8 and a two-drive mirrored RAID I do backups by cloning the RAID onto an other disk (in bay three) using Intego's Personal Backup X4.
Now it may happen that there is some kind of data loss or an other emergency case that urges me to boot from the cloned HD. I would do this by simply removing the HD in bay one and replacing it with the clone, then restart the server (second HD of the RAID1 remains in bay two).
The information I got until yet says that the mirrored RAID is then broken and needs to be completely re-build. Is this correct so far ? I originally assumed that the clone "remembers" that it was part of a RAID system before and rebuilds automatically with the second HD still in place. Very likely wrong ?
So if I need to rebuild the clone from scratch, which steps do I follow exactly ? As far as I understand I have two choices:
(1)
Via command line (as root): diskutil createRAID mirror <set name> Journaled HFS+ <device identifier disk1> <device identifier disk2>
<set name>: Would be volume name of the RAID to create, right ?
<device identifier disk1/2>: What is this and how to determine ?
(2)
Via disk utility: Select one disk (first line on the left disk/volume list, e.g. "76,2 GB Hitachi 123ABC"), click in "RAID" tab, do settings.
Then drag & drop each harddisk from the left to the right list (again, the first line of each disk entry). Finally creating the RAID by clicking at the button "Generate".
I'm not sure, although I would likely handle this with the disk utility, it appears easier to me using the diskutil command in terminal. But maybe I simply lack of explaining the GUI... let me know how to post images and I will add some screenshots here.
Well, if my proceedings are too complex and there is something easier, please let me know. I'm open for everything.

>This part of my question originally referred to the fact that when booting from the cloned backup in bay one while still having the second disk of the old RAID in bay two, it could occur that the OS rebuilds the RAID by using the data on the remaining mirror disk in bay two, couldn't ? This would be not desired, because the data on that disk would be no longer usable. So just for clarification, not that we have a misunderstanding in this point.
I see what you're getting at, and I don't believe it's an issue.
Given three disks, disk0, disk1 and disk2, where disk0 and disk1 are mirrored and that mirror fails, the OS will not rebuild the mirror using disk1 and any other disk. It won't arbitrarily choose any disk in the system to rebuild on - you have to specifically mark as disk as usable, either by enabling auto-rebuild and adding a spare disk to the array, or by using 'repairMirror' and specifying the disk to use.
In any case, if you reboot the system from disk2, there is no way it will rebuild the array using that disk since that disk is the active boot drive and can not be unmounted (which is necessary before being added to an array).
So, no, there is no chance that the system will auto-rebuild the working half of the mirror with your backup disk.
>Okay, let's summarize... I would follow this procedure in order to boot from the cloned backup and build a new RAID:
1. Remove both disks from the XServe.
2. Insert the cloned backup disk and boot.
3. Open terminal, su root, execute:
diskutil enableRAID disk0
diskutil repairMirror disk0 disk1
This is not correct.
When you 'enableRAID disk0' the OS will create a new, virtual disk (likely 'disk2'). This is the mirror array (currently consisting of only one drive), and it is this virtual disk that you need to specify as the mirror to be repaired.
So, given disk0 and disk1 as being the physical disks in the server, the steps are more likely to be:
<pre class=command>diskutil enableRAID disk0</pre>
(this creates a new, virtual disk2)
<pre class=command>diskutil repairMirror disk2 disk1</pre>
(this adds physical disk1 to the degraded mirror disk2)
When complete disk2 will be a mirror RAID consisting of disk0 and disk1.
>When using "diskutil enableRAID", I cannot determine the label of the RAID as I would do with "diskutil createRAID" (in command line manual this is referred to "setname"). Which setname does my "new" RAID system get, a default one ?
You know, I have no idea
I've never noticed this before. If I think about it, I'd guess that the setname is based on the source disk name.
>> If you add a drive to a RAID it gets reformatted, so it doesn't matter what's
on it.
Even if it was part of the RAID system before (the original disk in bay two) ? It could still have the RAID information on it and try to rebuild RAID when getting mounted, couldn't ?
No. See my comments above. The OS won't auto-rebuild unless a) the RAID is set to auto-rebuild and b) there is a spare disk in the array. If either of those two conditions are not true then the disk acts as a degraded mirror and can be reformatted/reallocated as you like.

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!

Fan Speeds, and Mirror Raid with New Internal Hard Drive

Regards,
I recently installed and formatted a new hard drive in my PowerMac dual 2.3 ghz computer and I have a few questions.
1. Now that there are two hard drives do I need to do anything to ensure that the fan on my computer can keep them cool? I think the fans I have in the hard drive bay is enough, but I do not know if they will automatically set themselves to run properly. I can monitor the fan speeds and temp from iStat pro, but do not remember what level the temperature was before installing the new one.
2. Given that my new drive is a SeaDisc hard drive and the older one is a Western Digital, will this cause any problems in creating a mirrored RAID. I believe that both are 7200rpm drives, and my second hard drive is a little larger (I will just have unused space after making the RAID). I am concerned with the fact that these two drives are from two different manufactures. Will this cause problems or drastically slow down the reading and writing of data? Has anyone else experienced problems in making a mirrored RAID from two hard drives that are not exact matches, and even come from different manufacturers?
Any advice will help.
Thanks
earpshmael

Hi earpshmael;
Generally when creating RAID arrays the more similar the drive the less problems you tend to have.
The real question is exactly why do you want or need RAID?
I think so many people seem to think that RAID will solve all of their problem. I hate to tell you the bad news but it will not.
Generally there are to varieties of RAID available using the software RAID built into OS X which are 0 and 1. RAID 0 or stripling is generally for moving large file rapidly for applications like HD video. It usually doesn't help the OS. RAID 1 or mirroring is for protection from drive failure. It is not a valid backup solution.
Allan

Mirrored raid and bootcamp.

On my mac i have a mirrored raid of 2 external hdds for music and photos etc.
I intend on buying a new mac soon, now I know I can just unplug and plug them into the new one no problem.
My question is though, that with my new mac i will be using bootcamp, and I am unsure what will happen if I boot into windows with my mirrored raid setup still plugged in.
Jonny

I'm going to try to install XP using an extra drive I have lying around and the Pro Caddy:
http://www.transintl.com/store/category.cfm?Category=2704
These keeps the 4 main drive bays free for OSX.

Mirrorred RAID Rebuild Failing

Hello,
I had a mirrored raid setup on 10.6.7, everything was working great for the last month, then today I went into disk utility and it said one drive failed. After checking the drive, there didn't seem to be any problem with its operation, so I can only assume it was a software/communication failure.
Clicking the rebuild button resulted in this error:
Rebuilding RAID set failed with the error:
POSIX reports: The operation couldn't be completed. Operation not permitted.
So I tried removing a disk, that also failed with the same error.
I then erased the failed drive which automatically removes it from the RAID configuration. Now when I try to add it back to the configuration I get the exact same error.
Has any experienced this issue and have any suggestions on how to get RAID back online?
Thanks in advance!
Michael

Thanks for your reply.
Yes, I am sure that the drives are working. I do not know what caused one of the drives to 'fail' as far as disk utility was concerned - but it was online when I checked it again.
I had issues while originally creating the RAID configuration, similar POSIX issues.
I have managed to get the configuration back online using the SoftRAID, but I am unable to create any new RAID configurations or modify existing ones using Disk Utility. Is it possible its an issue with POSIX and the drive USB drivers? Though I have tried with 3 or 4 different brand drives.
SoftRAID allows the drive set to be converted to a Disk Utility set after creating/repairing it - so thats what I have done for now.
I will try to setup/repair this all again once I have Lion installed and see if they fixed it in that version.
Any suggestions on how to get Disk Utility's RAID configuration on a Intel Core 2 Duo Mac Mini would be appreciated. I have filed a bug report with Apple as well. SoftRAID was a suggested alternative to a few other posts on the discussions for similar issues.
Michael

Degraded mirrored raid- won't rebuild

I've had 2 500 gig drives mirrored. When I set up the drives I did not check "automatically rebuild".
I just discovered ( not too long after installing Leopard) that one slice was "damaged" and the raid was degraded. I tried to rebuild, but got an error message that said disk utility was unable to recognize the filesystem. I finally erased the "damaged" drive, verified it and am ready to try rebuilding the set, but don't want to lose data from the remaining drive from the original raid.
How should I proceed?
Thanks-
Ford

Well I'm sure VERY few people have multiples of EVERYTHING. I still have my data.
All I want to do is mirror a fresh drive with the other drive that was part of a mirrored raid set. That should be possible... it seems...
Please don't admonish me for not having more backups. I have a total of 1.25 terabytes of HD space with a lot of redundancy.

Possibly boneheaded question re mirrored raid

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