Disabling Spotlight indexing on external volumesEdit

3/7/2026

Disabling for specific volumes

According to "Spotlight on search: How Spotlight works" (2021-01-08)

The simplest way to exclude volumes and folders from Spotlight’s database is to add them to the Privacy list in the Spotlight pane, in System Preferences.

It also notes that the trick of:

putting an empty file named .metadata_never_index inside the folder; this no longer works in recent macOS.

(2026-03-07): I tested adding removable (USB) volumes to the ignored volumes list. It seems that once unmounted, they disappear from the list. On remounting, they do not reappear in the list. However, perhaps because of the setting below, when I insert one of these volumes again, mdutil -sa does report the following:

/Volumes/Nemesio:
    Indexing and searching disabled.

Disable for all external volumes

Claude tells me this setting might work, but I don't have confirmation of that:

sudo defaults write /Library/Preferences/com.apple.SpotlightServer.plist ExternalVolumesIgnore -bool true

Kagi indicates the original source is "Disable Spotlight indexing of network volumes" (2015-09-15; see also web.archive.org snapshot):

To have mds ignore all external volumes including network volumes run the following command:

$ sudo defaults write /Library/Preferences/com.apple.SpotlightServer.plist ExternalVolumesIgnore -bool True

To be able to re-enable indexing for certain external volumes, run this command instead:

$ sudo defaults write /Library/Preferences/com.apple.SpotlightServer.plist ExternalVolumesDefaultOff -bool True

The page then goes on to describe how the author uses the Hopper disassembler to find candidate strings in the mds binary, eventually leading to:

  • CFPreferencesGetAppBooleanValue
  • ExternalVolumesIgnore
  • ExternalVolumesDefaultOff

And these log messages:

  • “ExternalVolumesIgnore” is set. All external volumes (except backup) will be ignored
  • “ExternalVolumesDefaultOff” is set. All external volumes (except backup) will default off, override with mdutil -i on

And ultimately with further digging establishes that kMDSPreferencesName is /Library/Preferences/com.apple.SpotlightServer.plist.

So, finally, the author sets the preferences then attaches a network volume, and finally confirms that the following log entry appears in /var/log/system.log:

9/15/15 10:14:08.486 PM mds[18428]: (Normal) DiskStore: "ExternalVolumesIgnore" is set.  All external volumes (except backup) will be ignored

FWIW, in my own testing (2026-03-07), I was not able to reproduce the log message in /var/log/system.log, but as noted above, when I reinserted one of my removable volumes, mdutil -sa reports:

/Volumes/Nemesio:
    Indexing and searching disabled.