The Background Download Interruption
To maximize battery life and reduce mechanical wear on internal components, macOS is configured to automatically put hard disks to sleep whenever possible. While this is an excellent feature for general laptop use, it can cause severe interruptions for specific workflows. If you are rendering a massive video project, running a local server environment, or downloading a 100GB video game overnight, the hard disk going to sleep can cause the entire process to stall, fail, or throw frustrating “Disk disconnected” errors.
How to Keep the Hard Disk Spinning
You can adjust your Mac’s energy settings to instruct it to never allow the hard disks to sleep while the computer is turned on, regardless of whether you are actively using it.
1. Click the Apple logo () in the top-left corner of the menu bar.
2. Select System Settings from the drop-down menu (or System Preferences on older versions).
3. In the left-hand sidebar, scroll down and click on Displays.
4. Click the Advanced… button located at the bottom of the Displays window.
5. Look for the toggle switch labelled Put hard disks to sleep when possible.
6. Click the toggle switch to turn it Off.
7. Click Done to save your changes.
Understanding Solid State Drives (SSDs)
It is important to note that this specific setting was originally designed for older, mechanical hard disk drives (HDDs) that physically spin down. Most modern Macs rely entirely on Solid State Drives (SSDs), which do not have moving parts and manage their own low-power states far more efficiently. However, if you have external mechanical hard drives plugged into your Mac via USB or Thunderbolt, changing this setting is absolutely crucial to prevent those external drives from constantly disconnecting and going to sleep in the middle of data transfers.