***Work in progress!***

Probably your CoreStorage Logical Volume got corrupted!

I recommend to backup your data to an external drive with Time Machine and rebuild the FusionDrive from scratch.

**Time Machine backup**

- To backup your main volume, boot to your main drive
- Attach an external drive. The drive has to be formatted as an HFS+ Journaled volume. Check this with Disk Utility. If necessary repartition the external drive. All data on the drive will be destroyed after repartitioning/formatting it. The drive has to have the size of the volume to back up (or more).
- Usually you will be asked if the external drive should serve as a Time Machine backup drive after plugging it in for the first time. If not, open Time Machine in the *System Preferences* and configure the external drive as Time Machine backup drive.

 [![enter image description here][1]][1]

 Hit *Select Backup Drive* and choose your external drive:

 [![enter image description here][2]][2]

 Turn on Time Machine. The backup will be started after a few minutes and will take some time depending on the size.


  [1]: https://i.sstatic.net/iRSiy.png
  [2]: https://i.sstatic.net/rsYHt.png