How to merge two Mac partitions? Recently I ran Boot Camp Assistant to install a copy of Windows 7. The "Partitioning Disk" process froze and I force quit it - I know, bad idea - and although I was left with a functioning Mac, I noticed that the Mac is split into two separate partitions. One is 2.2 TB, and one is 801.44 GB (I have a 3 TB Fusion Drive). Previously they showed up as one single partition. When I launch Disk Utility, either from Utilities or Internet Recovery Mode, I get "The full size of the Fusion Drive is not available for repartitioning.", and I'm unable to delete/adjust either of the partitions (all the options are greyed out).

I have Time Machine and I have a separate HD backup, so I don't mind reinstalling OS X - in fact, I want to - but I want to fix the Mac hard drive so that everything appears as one cohesive partition, but I'm not sure what to do.

I found this site - http://www.rawkode.com/blog/2014/2/12/osx-fusion-drive-boot-camp-assistant-disk-utility-recovery - which seems to do what I want to do, but I'm hesitant on using "deleteVolume". I'm not sure which logical volume value to enter, and I want to ensure that if I delete a volume or whatever, I'll still be able to reinstall OS X (and if I reinstall OS X, I'd like for there to still be a Recovery Mode, just in case).

Here's a picture of my Disk Utility:

diskutility http://www.pixelrealism.com/diskutil.jpg

Any help is appreciated. Thanks!
Try to run Disk utility upon system start up, this may increase functionality. So delete second volume and extend  Macintosh HD by dragging it down to make as a single unit. Also repair disk and permissions.

From the screenshot I noticed that you selected your boot disk, which is not possible to edit while OS is running, however second split of HD should be editable. To make less confusion, consider renaming HD, for potential data prevention while modifying HD