Missing HD Space in iMac Fusion Drive

arsenalgear

macrumors regular
Original poster
Dec 17, 2007
100
1
Hi,

I was having problems with my late 2013 27" iMac slowing down to molasses. To make a long story short, I removed my Boot Camp partition in internet Recovery Mode (command-option-r) using Disk Utility and the Partition feature instead of Boot Camp Assistant (really dumb mistake). I selected the partition, clicked the minus button, and clicked Apply. Everything seemed to be proceeding as planned until about 3 hours into the process, I received a spinning disk. I left the computer running for 3 days until today I decided to force shutdown the computer as I thought it was not doing anything. I started the computer in internet Recovery Mode, went to Disk Utility, and it is showing my Fusion Drive as 2.09 TB instead of 3.09 TB, so basically it is not showing the Boot Camp partition in Disk Utility, but it is still showing that 1 TB is not available. I reinstalled macOS Sierra, and when I go to Disk Utility > Partition, under Device Information it does show the size of the HD as 3 TB but only shows one partition and it lists the partition size as 2.09 TB.

Could someone please tell me how I can recover this missing space and basically reset my HD as new?

Thank you very much!
 

arsenalgear

macrumors regular
Original poster
Dec 17, 2007
100
1
https://forums.macrumors.com/threads/i-think-i-just-broke-my-new-imac.1973683/

Make a backup then follow the steps in my posts #6 and #14 to wipe both drives back to one partition each and recreate the Fusion drive. Then restore from the backup.

If you need more help with steps, let me know.

If it is any consolation, you are not the first person to do this. :)
When I type
Code:
diskutil cs delete "Macintosh HD"
, I get the following in terminal:

Code:
 Macintosh HD does not appear to be a valid Core Storage Logical Volume Group UUID or name
Could you please advise what I should do next?
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
30,459
10,263
California
You will need to put whatever your drive is named in that section. The default is Macintosh HD. It looks like yours is named something else. If it is "Arsenal Drive" for example, use that in quotes for that part of the command.

Just open Disk Utility and you will see the drive name.
 

arsenalgear

macrumors regular
Original poster
Dec 17, 2007
100
1
You will need to put whatever your drive is named in that section. The default is Macintosh HD. It looks like yours is named something else. If it is "Arsenal Drive" for example, use that in quotes for that part of the command.

Just open Disk Utility and you will see the drive name.
Thank you so much for your help in getting this issue resolved! With your input, I was able to get the problem fixed. Actually, my hard drive is named "Macintosh HD", but I could not figure out why it delivered that error. So, I opened Disk Utility, selected "Fusion Drive", and then clicked "Info". I noticed that the Volume type said "Internal Drive", so I entered the following code in Terminal:

Code:
diskutil cs delete "Internal Drive"
The Fusion Drive separated and I was able to erase the 3 TB platter drive in Disk Utility. Note that Disk Utility did not prompt me to fix the drive.

I then ran "diskutil list" in Terminal and noticed that I had a "disk0" and a "disk2". I then ran the code "
diskutil cs create fusion disk0s2 disk1s2" and received an error as "disk1s2" could not be located. So, I then switched the code to the following so it mentioned my disk2:

Code:
diskutil cs create fusion disk0s2 disk2s2
I was then able to proceed with the rest of the code per your post and was able to recreate the Fusion Drive.

Again, thank you so much for your help! I always find the moderators and members of the MacRumors Forum more helpful and knowledgable than Apple Support. :)
 
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