I believe that the small partners who have worked on the partitions under Mac OS, or how many will encounter "failed to modify the partition map because the file system verification failed" error prompt. Some may be installed before the bootcamp version of the Windos system, now want to delete, but also deleted. Have a hand cheap time, after installation, consider half a day to delete. When I see this error situation, my heart is half cold, a large disk space to see again, do not know how you feel at this time. The following is a brief description of what to do when you encounter such a situation.
1. When encountering the above situation, this is because the Mac OS system internal file system in the validation error, resulting in the inability to merge the spare partitions into the Mac OS partition. Please reboot the MAC system and press the Command+s key on the keyboard to enter Safe mode during reboot. If not, try a few more times before restarting to hear the sound.
2, then you will see on the screen a string of notes in the beating, when not moving, press the keyboard "enter" button, appear command prompt, as shown in the picture
3, then please enter the Fsck-f command, and press the keyboard "enter" key to execute the command.
4, then please wait for the repair file system, repair speed will be based on the speed of the hard disk, as shown in the figure
5, when the repair is complete and see the screen prompts "the volume Macintosh HD was reaired successfully", the description has been successful, as shown in the figure
6. Next, please enter the reboot command to restart the computer from Safe mode.
7, after the restart, and then open the Disk tool, the partition will be merged.