Fix fusion drive partition mess from bootcamp assistant

bootcampfusion-drivehard drivepartition

I have a self made fusion drive on a 2009 iMac using a 256gb ssd and a 3tb hard drive. After the 10.8.3 update yesterday I tried to create a bootcamp partition but unfortunately it failed after hours. I had a look at the hard drive manager and the bootcamp partition (I've set it to 303gb) was already there. After having a closer look i noticed that the partition was in the middle of a 1.7 tb partition which was now used for the fusion drive and a 800gb partition that wasn't used anymore. It looks like the bootcamp assistant failed while moving the partition around on the drive.

I started the assistant again to make him remove the partition again which I did but still left the hard drive split into two parts – the 800gb part is still unused and unusable.

Here is what diskutil cs list says:

enter image description here

Does anyone have a hint for me how I can merge these 800gb part into my fusion drive again?

Best Answer

The surefire fix is to format everything and recreate your Fusion Drive, then restore from a backup.

Hopefully someone can help us fix this another way, but my research shows that non-destructively merging content onto a live fusion drive isn't supported by Apple or another tool chain yet.

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Restoring Fusion Drive after error on partition erase

The way to deal with this is by separating the fusion drive, reformatting each drive, and recreating them. I suspect what's happened is your Mac cannot recognize the NTFS formatted portion of the disk.

Reboot while holding Alt + Cmd + R for Internet Recovery Mode. Go to Utilities > Terminal, and in terminal type: diskutil cs list, then find the UUID under "Logical Volume Group" with the missing space, copy it, and paste it after: diskutil cs delete. Go back to Disk Utility. At the prompt, click "OK" to repair your Fusion Drive. Exit Disk Utility, reboot (to the recovery partition if it doesn't automatically, to Internet Recovery Mode, or using a recovery USB drive) and reinstall OS X. When that finishes: If you plan on restoring from a Time Machine backup, you may have to create a new User and recover your old account logged in as the new one. If this does not work, you may have to manually reformat each drive, and proceed from step one.

Messed up 1TB Fusion Drive Partitions (on iMac 5K)

To expand your CoreStorage Logical Volume Macintosh HD you have to delete the blocking NO NAME EFI partition (disk1s5). The two unnamed parts (138.62 GB and 99.9 GB) are no partitions but unallocated disk space.

To remove the second EFI partition (and expand Macintosh HD) you have to boot to Internet Recovery Mode or an OS X system on an external device.

Preparation:

Backup your data.
Detach any external drive (especially your external Time Machine backup drive).
Restart to Internet Recovery Mode by pressing alt cmd R at startup.
The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot to a recovery netboot image which usually is loaded from an Apple/Akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (Mavericks, Yosemite or El Capitan) or a thumb drive/external disk containing a full system (Mavericks, Yosemite or El Capitan). If you boot from a full system on an external volume and login as a user with admin permissions (which is required) you have to prepend sudo for the gpt command below.

Remove the second EFI partition and modify CoreStorage stack:

Open in the menubar Utilities/Terminal

First you should get an overview of your disks and the partition layout:

Enter diskutil list and gpt -r show /dev/disk1 (assuming disk1 is your HDD)

To resize the CoreStorage volume you have to delete any blocking partition first (the Recovery HD doesn't count because it usually will be moved with the resizeStack command).

First you have to unmount all mounted volumes on disk0 and disk1 (first the CoreStorage volume, which has its own disk identifier (e.g. disk3) but resides on disk0 and disk1) then all other Fusion Drive disks (assuming disk0 = SSD/disk1 = HHD. Please check the diskutil list output for the proper disk identifiers and replace them in the commands below if necessary):
```
diskutil umountDisk /dev/disk3
```
then additional disks. Example:
```
diskutil umountDisk /dev/disk0
diskutil umountDisk /dev/disk1
```
Remove the second EFI partition (assuming the 103 MB partition has the index number 4 in the gpt listing you got earlier)
```
gpt remove -i 4 /dev/disk1
```

Remount all disks in the reverse order

diskutil mountDisk /dev/disk0
diskutil mountDisk /dev/disk1
diskutil mountDisk /dev/disk3

Since any blocking partition is deleted you may now resize the CoreStorage volume with
```
diskutil cs resizeStack LVUUID size 
```
in your example that's
```
diskutil cs resizeStack 5E88EF38-D2A8-4A7D-8508-5C24D948877D 1100g 
```
to expand it to ~1,1 TB (or 1100 GB) or
```
diskutil cs resizeStack 5E88EF38-D2A8-4A7D-8508-5C24D948877D 0g 
```
to expand it to the full available size (0g is a magic number here).

The Recovery HD partition (disk1s3) will be moved to the end of disk1 automatically.
Quit Terminal and reboot to Macintosh HD

Best Answer

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