OSX Yosemite can't resize partitions? A few weeks ago I installed OS X yosemite.I did it on the standard partition, but I had a dual-boot with ubuntu.
I realised that the ubuntu boot was gone so I tried to redo it.
But in disk utility, when i tried to make Macintosh HD smaller it gave a
"Error: -69803: Couldn't modify partition map because file system verification failed
"

How do I fix this, not just for dual booting but resizing partitions?
Boot holding  Command ⌘    R  at the chimes to boot into Recovery Mode, run Disk Utility &amp; Repair Disk.