Mac Pro - Undo Apple RAID

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Level 1

9 points

Mac Pro - Undo Apple RAID

Hello,

I want to upgrade my OS from Yosemite to El Capitan, however, I'm unable to because my hard drive is part of an Apple RAID. I also want to run Boot Camp, but I can't due to the same reason. Is there a way for me to undo the Apple RAID?

Another issue I'm having is one RAID set is failing. Would it be possible for me to just remove that hard drive, since I don't need that much storage?

Background story: Mac Pro was purchased used already had a RAID, so I don't know much about Apple RAIDS.

Any help is much appreciated!

Specs:

Mac Pro (Mid 2010)

Version 10.10.5

Processor 2 x 2.4 GHz Quad-Core Intel Xeon

Graphics 32 GB 1066 MHz DDR3

Posted on May 23, 2018 10:47 PM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

140,297 points

May 24, 2018 7:53 PM in response to mh.tran

If you remove one failing drive from a Mirrored RAID set, the set continue to be a RAID (with all its restrictions) -- it is just waiting for you to add a spare to the set so that the set can be rebuilt.

To remove an Apple RAID, copy the data off to at least one and preferably two backups.

Then ERASE the drive and give it the usual default settings for macOS drives. (GUID partition Map, HFS+ extended Volume)

Or take this opportunity to switch to a drive that better meets your needs, such as a fast SSD drive. If you do not have enough open drive bays, any number of drives, including a new Boot drive, can be set up and used in External enclosure(s).

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Answer 2

May 25, 2018 12:33 PM in response to mh.tran

All the panes you are showing are entitled RAID. There will be no options to do anything but keep using these four drives as a RAID on those panes.

The RAID Volume is the Boot Volume. You will need a different Boot drive (or Disk Utility running from an Installer DVD or Installer USB-stick) as your Boot Drive to ERASE those drives. You cannot erase the Volume you are booted from -- that is like sawing off the branch you are standing on.

To eliminate your RAID, (presuming you Trust your Backups) use the ERASE Pane, select a drive by Hardware-name to be sure you are erasing the ENTIRE Drive, and click ERASE.

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Answer 3

May 25, 2018 1:21 PM in response to mh.tran

boot in recovery mode and attempt those steps again in disk utility,

RAID drives do not support Recovery, and your Mac does not support Internet recovery.

You need to install MacOS on an external drive, or get a 10.6 Installer/Utilities DVD (both are on the same DVD), or make a USB-stick Installer to get access to Disk Utility.

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Answer 4

mh.tran Author

Level 1

9 points

May 24, 2018 9:46 PM in response to Grant Bennet-Alder

Thanks Grant!

I plan on removing the failing drive and doing as you suggested for removal of the raid. I've already backed up my data, but I am unsure on how to get started with the process. The main drive is Stipe of Both Mirrors, however, there is no tab to erase it. After clicking on the Macintosh HD, it says the format Mac OS, so I wouldn't erase that, right?

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Answer 5

mh.tran Author

Level 1

9 points

May 25, 2018 12:32 PM in response to Grant Bennet-Alder

Ahhh okay, that makes perfect sense!

I had previously tried erasing the raid sets/slice by hitting delete, erase, and even using the erasedisk command in terminal, but none of those worked. Next, I was planning to try and boot in recovery mode and attempt those steps again in disk utility, or to physically remove the drives and then deleting the raids, but I'll try booting from a USB stick and get back here with an update.

Thanks again!

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Answer 6

mh.tran Author

Level 1

9 points

May 25, 2018 2:52 PM in response to Grant Bennet-Alder

Good thing I did not try that then!

Here is step by step process of what I've done so far:

Removed the failing hard drive, so now there are 3 hard drives in the bay
Created a bootable USB
Booted into Disk Utility
The only hard drive that appeared in Disk Utility was "Macintosh HD"
Erased "Macintosh HD" and then deleted the raid
This is where I started freaking out because after deleting the raid, "Macintosh HD" completely disappeared from Disk Utility
Restarted and booted back into Disk Utility
The other three hard drives/raids from the bay appeared in Disk Utility this time, but no "Macintosh HD"
Same process to each hard drive– erased and then also deleted raids
Restarted, held option key, only bootable USB appeared and not the other hard drives
Went ahead and Installed Mac Sierra on one of the three hard drives from the bay

The new OS is currently being installed. Now, here are my concerns:

Why did "Macintosh HD" just disappear from Disk Utility in Step 4?
Was that the main hard drive that was not in the bay, but in the tower itself?
Should I be worried that it disappeared?

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Answer 7

mh.tran Author

Level 1

9 points

May 25, 2018 3:43 PM in response to mh.tran

Update 2:

The install was successful. No more RAIDs, time to set up Boot Camp. Again, thank you for the help, Grant.

I'm still concerned about where the original "Macintosh HD" disappeared off to because its capacity is 2TB and I would rather install my main OS on there. Any ideas?

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Answer 8

May 25, 2018 8:03 PM in response to mh.tran

Macintosh HD logical Volume, a Striped RAID built from two Mirrored RAIDed drives. Its capacity was 2TB, but it required 4 1TB drives to create it.

Striped RAID is problematic because a failure leads you with no way to recover -- alternate stripes are on alternate drives -- or in this case, on alternate Mirrored RAID sets.

You are probably better off using some of your drives for Backups.

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Mac Pro - Undo Apple RAID

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