Can not delete Free Space on iMac 5K: Partition doesn't appear in CS list

Solution 1:

Preliminary remark

Like bmike already mentioned: the path

• back up the CoreStorage Volume to Time Machine
• and then erase / repartition both and start over with a new fusion drive

should be preferred.

Preparation:

• 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 into 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 or Yosemite) or a thumb drive containing a full system (Mavericks or Yosemite).

  Below I assume that the disk identifier of your Internet Recovery HD (OS X Base System) or thumb drive is disk2, disk0 is your SSD, disk1 your HDD and disk3 your CoreStorage Logical Volume.

'Repair': (not recommended because of potential data loss)

• First try to check the volume 'Macintosh HD' with Disk Utility. If the volume is corrupted consider a backup - if possible - and a reinstall of Mac OS X.

• If the volume is OK quit Disk Utility

• Open Terminal and enter diskutil list, diskutil cs list, gpt -r -vvv show /dev/disk0 and gpt -r -vvv show /dev/disk1
• with the informations found in the different listings enter diskutil unmountDisk /dev/LogicalVolumeIdentifier and both diskutil unmountDisk /dev/DisksContainingApple_CoreStorageIdentifier
  In your case: first enter diskutil unmountDisk /dev/disk3, then diskutil unmountDisk /dev/disk0 and diskutil unmountDisk /dev/disk1
• remove the EFI NO NAME partition with gpt remove -i IndexNumberOfEFINoName DiskIdentifier:
  In your case: gpt remove -i 4 disk1
• Remount the CoreStorage disks and then the Logical Volume:
  In your case: first diskutil mountDisk /dev/disk0 and diskutil mountDisk /dev/disk1 and then diskutil mount /dev/disk3.

• enter gpt -r -vvv show /dev/HDDApple_CoreStorageIdentfier to get verbose partition data of your HDD CoreStorage disk.
  In your case: gpt -r -vvv show /dev/disk1
  It should look similar to the example below:

  Thomass-iMac:~ moneill$ sudo gpt -r -vv show /dev/disk1
  gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168
  gpt show: /dev/disk1: PMBR at sector 0
  gpt show: /dev/disk1: Pri GPT at sector 1
  gpt show: /dev/disk1: Sec GPT at sector 1953525167
         start        size  index  contents
             0           1         PMBR
             1           1         Pri GPT header
             2          32         Pri GPT table
            34           6         
            40      409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
        409640  1409895488      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
    1410305128     1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
    1411574664   541950471       
    1953525135          32         Sec GPT table
    1953525167           1         Sec GPT header
  

• The free space consists of 541950471 blocks here.

  Calculate the biggest block number dividable through 8. That are 541950464 blocks (á 512 bytes) which equals 277478637568 B or ~277.5 GB.
  Add the size of your HDD CoreStorage Physical Volume (721866489856 B in your case).

  The result is 277478637568 B + 721866489856 B = 999345127424 B

• Resize your HDD CoreStorage physical volume with diskutil cs resizeDisk HDD-PVUUID newsize
  In your case: diskutil cs resizeDisk 93E06B6F-E206-419D-9ED7-16426463BB3E 999345127424b
• Calculate the maximal size of your CoreStorage Logical Volume (refresh diskutil cs list) = size disk0s2 + size disk1s2.
  In your case that's 120988852224 B + 999345127424 B = 1120333979648 B. That should also be the size of your extended Logical Volume Group (check diskutil cs list).

• Resize your Logical Volume with diskutil cs resizeVolume LVUUID LVGSize-128 MB. In your case that's diskutil cs resizeVolume DD3595D9-58B6-4745-8EC9-816F9ABE30E9 1120205979648b. If you get an error (There is not enough free space...) choose a smaller size like 1120141979648b (=LVGSize-192 MB).

  Magical numbers like diskutil cs resizeVolume LVUUID 100% or diskutil cs resizeVolume LVUUID 0g sadly don't work here - at least for me.

• Quit Terminal and open Disk Utility.
• Check your expanded CoreStorage Volume for errors.
• Quit Disk Utility, choose your now expanded CoreStorage volume as startup disk and restart your Mac

Solution 2:

Thanks to @klanomath for a great answer. It's amazing to me that the only way to do this is such a destructive one. I will outline here a few things I learned and maybe a little bit of an abstraction of the problem.

• The FusionDrive, as the name suggests, is actually two physical drives fused together.
• Occasionally when setting up BOOTCAMP, the Windows partition is corrupted or otherwise screwed up. Of the three times I tried to set up a Win8.1 BC drive two failed this way.
• The Windows partition is impossible to remove using the Disk Utility or the diskutil command in terminal.
• You can not add or alter the partition.
• DiskUtility UI can not alter these, even in Recovery Mode.
• What you need to do is, in a nutshell:
• Back up your system using Time Machine
• Boot into Recovery Mode using either Internet Recovery
• Launch TERMINAL under UTILITIES and, using the command line, delete the Logical and Physical partitions
• You then are left with an SSD (128GB) and an HDD (988GB) (adding up to 1TB in my case)
• You then re-fuse these two together using the command line and re left with an empty 1TB (in my case) drive
• Finally, you plug in your Time Machine back up and restore

I don't know but none of the descriptions made it clear what was actually happening so I thought I'd provide this answer. The details in the above thread work well but when I finally clicked on what I was doing, I thought I'd share.

I find it crazy that OS X's Disk Utility a) screws this up so badly and b) can't fix it without a full reformatting!