Why El Capitan needs an SSD or Fusion Drive, and all about their care and maintenance.
diskutil
Disk errors and crashes may be terminal, rescuable, or fully repairable. Understanding their nature enables you to choose how to tackle them.
Disk Utility may seem the most mundane of all the utilities, but together with its command shell partners packs a real punch in several important areas.
The Eclectic Light Company 