Put hard disks to sleep when possible
This Energy Saver setting powers down the hard drive motor when you aren't reading or writing files from the drive. This setting only works with computers that use mechanical hard drive mechanisms to store data. Consider deselecting this option if you are using an application that works better with continued read and write access to the hard disk, such as a pro audio or video editing app.
Note: Solid-state drives (SSD) do not use a motorized mechanism to read or write data. For Mac computers that only include a built-in solid-state drive, this setting does not affect the built-in drive. It only applies to externally connected, mechanical drives.
