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

Similar Messages

Creating a mirrored raid set with a hard drive that already has data on it.

I have a hard drive that I keep my photos on, and want to create a mirrored raid set that includes this drive, with its data, and another drive. How can I do this without erasing the drive with my photos on them? I am running 10.7.5 if that matters.
Thanks for any help.

Creating a Mirrored RAID reformats the drive and loads a substantial RAID driver and some tables onto it. When completed, the drive is inherently a member of a RAID set, and will continue to be so even if moved to another Mac.
because of this, you cannot create a RAID directly on a standard drive that contains data already in any reasonable, risk-free way.
To amplify what The Hatter has said above, Mirrored RAID is not Backup. Mirrored RAID only increases mean time to repair to keep a drive failure from becoming a Data Disaster. You still need a Backup. Mirrored RAID does not protect you from deletions from user error, crazy software, or "just because".
I run a mirrored RAID in my Home Server, which contains all the Users files for everyone in the Household. And I also recognize (after being burned by it) that Mirrored RAID is helpful, but not a sufficient Backup by itself. I back up the Users Drive automatically to an External drive using Time Machine. [So what I am advising is not just theoretical, I am living what I am advising.]
With WD Black 1TB and other very good drives in the under US$100 range, there is really no reason NOT to invest in several drives for such an undertaking.

Offline Disc In Degraded Mirrored RAID Set

I have a 2 disc (300GB each) mirrored RAID set that has worked fine up until recently. One slice appeared failed so I attempted to rebuild it. 7 hours later it still showed up as failed. I attempted a rebuild once more and the same result. I then shut everything down and re-booted my whole system. Now the RAID set is still degraded but the slice now shows up as offline as opposed to failed.
I checked the connections and it's all connected fine.
I have run First Aid several times and no repairs were necessary.
Anyway I can get this back 'online'?
If not, can I delete it, repair it and if it's repaired add it back to the RAID set?

It sounds like one of the drives in the mirrored set has lost its mind (i.e., failed).
This is exactly the situation Mirrored RAID is good for.
Remove the failed drive, insert your spare drive of the same or larger size, and assign it as a spare. Then you should be able to get the RAID to rebuild onto the spare and bring it up to date in the next half-a-day or so. Then the mirror will show as working again.
Make sure your Backup is up-to-date. A second failure now (before the array has rebuilt) will give you data loss.

Mirrored RAID set deletion

Hi all,
I've set up two USB disks as a mirrored RAID set connected to my MacBook.
Now, I want to remove this RAID set (since it doesn't work so well for me).
In the manuals, Disk Utility is said to split nicely a mirrored RAID set, resulting in two disks with the same contents, when removing a mirrored RAID set.
However, when I try to do it, Disk Utility warns me that all data on the disks will be lost (which should not be the case...).
I can't afford to loose all data (120GB of photos), and I can't easily make a backup (120GB of data is tough to backup !)
Who should I trust ? Disk Utility or the manual for Disk Utility ?
Will my data be lost or not when I delete this mirrored RAID set ?
I need an authoritative answer... Could someone help me ?
Thanks,
Chris

Thanks for your advice... but if no RAID disk is plugged in, the RAID does NOT show in Disk Utility.
As I understand it, the partition scheme is different when using RAID... So a disk that is part of a RAID set has to be modified to get out of the mirror...
But it seems Disk Utility cannot disconnect a single disk from the RAID.
My RAID is now out of sync, and I won't attempt to resync it again...
So I would like to remove the whole RAID thing, and just get two disks, one that will be reformated, and one where all the data should be kept...
Later this week, I'll have access to another (afaik Firewire) disk... So I'll make a backup and simply try to delete the RAID... If it goes wild, I'll have that backup to recover.
I'll keep you posted if I can.
However, things should be made clear somewhere : either in the docs or in Disk Utility... I submitted some comments about the documentation on apple's website.
Bye
Chris

Mirrored Raid Set

I have two disks arranged as a mirrored RAID set and wonder how I will know when one of the disks fails and which one it is.

Mirrored RAID is sort of worthless for most all users as anything bad happens gets immediately copied to the other drive.
Your better off with scheduled clones, this way every so often it will remind you to hook it up and update it, or leave one hooked up and it will update itself.
You get both hardware AND software protection as you only update when you know it's good.
Also you can keep several clones backdated, and they are all independently bootable.
Most commonly used backup methods

See HDD failed in Mirrored RAID Set

Could you please kindly tell what steps should I do to fix failed Harddisk as below? Many Thanks.

Thanks for the answer. Do you have any pointers to how to identify from device name, which physical hard disk it is? For example, I have a RAID1 mirror set, the devices are disk1s3 (failed) and disk4s2. These are partitions on 2 different external disks. How do I know which one disk1s3 is? Is there a way to reconcile it with the hardware?
I suppose I could unplug one of the disks and see what happens, but that would be disruptive and extreme. What would happen to the RAID set, what if Time Machine is running to the mirror?

Mirrored RAID set has degraded following power outage.

Hello,
Following a recent power outage our Mac Pro running Leopard OSX Server with 2 x 1TB discs in a Mirroring RAID configuration (with an installed RAID card) developed a 'severe error' message.
The Raid Set R0-1 has a Viable (degraded) status.
Drive One (or bay 1) is 'Good' and 'Assigned'
Drive Two is 'Good' but with the State - 'Roaming'
Also, the events display describes the failure of a drive 3 (there isn't one) and that the R0-1 is Degraded and no spare is available.
So, we're a little confused.
1. Is the Drive 2 no longer part of the RAID mirror (i.e. Roaming)
OR
2. Something more significant has happened hence the bogus Drive 3 message?
Any suggestions or advice would be much appreciated as always.
Thanks
Steve

Yes. Verification with the GUI tool is the first step. But... hmm, if you are dropping communications with the card, that is not a good sign. Make sure you have a backup and then try a PMU reset on the system. Maybe there is something wacky in the power manager. Then try any/all of these from Terminal to get more information:
raidutil list status
raidutil list eventinfo
raidutil list raidsetinfo
This should provide feedback. If these commands fail, then I fear that the card is not responding. Do you have AppleCare? It might be time to call for a replacement card.
Hope this helps

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.

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.

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.

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!

Upgrading Xserve with RAID set

Hi,
I have been asked to upgrade a copy of Server 10.3 to 10.4. I don't like upgrading, so will do a clean install and then restore all of the SA and WGM data back into the server. Here is the question:
The XServe has 3 bays - bay 1 has the startup disk and bay 2 and 3 have a mirrored RAID set. Is the RAID config data held in the OS, so if I reinstall the system will the configuration data for the RAID set be lost and will I have to re-RAID the server? Or is the config data stored on the drive and so a re-install won't affect the RAID set?
Many thanks,
JS
iMac G5 17" 2 Ghz, 1 GB RAM, 600 GB HDD Mac OS X (10.4.9)
iMac G5 17" 2 Ghz, 1 GB RAM, 600 GB HDD Mac OS X (10.4.9)
iMac G5 17" 2 Ghz, 1 GB RAM, 600 GB HDD Mac OS X (10.4.9)

I would like to know if the RAID 'config' data is
actually written onto the drive or is stored in the
OS. I first thought it would be stored in software
because Disk Utility uses software RAID, but then
again a single drive has the partition data on the
drive.
James,
If you think about it a bit, software RAID information has to be on the drive because the volume becomes a RAID before a filesystem is created and before an install is done. Likewise, a hardware raid is done on the interface card and comes up the same way. Neither can know which of the members of the mirror are available at first boot; otherwise, there would be a single point of failure during boot, and the whole purpose of a RAID 1 mirror would be lost.
The bootstrap starts on the mirror primary, then, as the driver is brought online and before any writes are done, the driver collects the members of the RAID 1 mirror set and forms the mirror. If the mirror primary isn't available, then the mirror secondary is used (which has an exact copy except for stuff indicating that it is the secondary). All this happens normally during boot, as if from a single non-RAID drive, until the cutover is made to RAID early in the driver intialization.
That's why booting from a RAID 0 (stripe) is so hard - all of the data is not present on a single drive. It can be done, but it is hard and requires special care during the boot.
You really do want to make the upgrade to AppleRAID 2 before spending time on the update, though. There are details in this article on afp548.com:
http://www.afp548.com/article.php?story=AppleRAID2-in-Depth
Russ
Xserve G5 2.0 GHz 2 GB RAM Mac OS X (10.4.8) Apple Hardware RAID, ATTO UL4D, Exabyte VXA-2 1x10 1u

How to delete a RAID set in Disk Utility?

I set up a mirrored RAID set with two 80GB disks on a 500MHz G4 "sawtooth", then installed Tiger successfully. Statup Disk on the Tiger DVD recognizes it as a valid startup disk, but it won't boot (stays on the white screen with the large apple).
So, I decided to go back to two separate disks with no RAID, but Disk Utility won't seeem to let me delete a RAID set. It shows the volumes as locked (no apparent way to unlock them), and also doesn't allow me to format the underlying drives (bad file descriptor error).
Any suggestions on how to undo a RAID set in Tiger?
Thanks,
0g
G4 "Gigabit" Dual-500 Mac OS X (10.4.8) 1.5GB RAM, 1TB internal, SCSI, 802.11g, USB2.0

Boot from your OS X Installer Disc. After the installer loads select your language and click on the Continue button. After the menubar appears select Disk Utility from the Utilities menu (Installer menu for Panther.) After DU loads select the main entry of the RAID (the one with the RAID size) then click on the RAID tab in the DU main window. Select the main RAID entry from the icon list (the one that says "Mirrored RAID Set" and should have the word "Online" in green. Then click the Delete button down below the list view.
Be sure to backup first because this could cause complete loss of data.
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Which hard drive to choose when a hard drive failed from mirrored raid

this is my mirrored raid set up from 4 ext HD to make a total of 2 mirrored ext HD raids. In one set, a HD is out of sync and has failed. I chose auto rebuild when I create the raids but it did not occurred. question-Which HD do I chose to rebuld when I use disk utility? Please see picture below. thank you.

any suggestion? or am i in the wrong discussion board.

Can't create a RAID set using the Utilities window

Hello! this seems so weird to me. I have 2 new LaCie 500GB drives. I'm working with ProTools (music production) and I need redundancy in terms of data safety, that's the reason for creating a mirrored RAID set. 500 GB should last me for awhile OK. Drives are brand new out of the box. They came formatted as FAT-32, got rid of that and erased and reformatted them as OS extended, journaled. They can be seen in system profiler. They mount and unmount OK. They can each accept and store files and I can retrieve files from them. But I can't join them to create a mirrored RAID set. In the disk utility window, I highlight the icon of either drive and try to drag it into the window but it won't drag. What's going on? I did this just fine with my earlier Lacie 200GB drives and an MBP, what's wrong here?
I have a feeling I'm doing something really basic and really wrong but I can't see it!
Anybody got any ideas? Thanks
Rick

It's subtle; I had the same problem and it took me a month to track it down.
It's not enough to reformat your new drives, you also need to repartition them to either GUID Partition Table or Apple Partition Map. Look and I'll bet your drives, properly formated as HFS+ (Mac, Journaling) are still however showing Master Boot Record as their partition scheme -- you'll need to re-partition them.
You need to use the "Options..." button when partitioning via the Disk Utility. You can choose whichever Map/Table is appropriate for your hardware from the window that opens.
My scheme: copy the data to one, repartition the second, copy the data back onto the second one from the first one, repartition the first one, copy the data back onto the first one from the second, and you should be good to go in setting up your RAID.

Mirrored RAID Set Questions

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