I have an HDD attached to my Mac for backups and as storage for photos which are archived. (I don’t think this is MacOS version specific, but for me this happened with MacOS Tahoe 26.7. The last couple of days I noticed that my disk was constantly rattling / spinning, to the point where it started to annoy me. I rebooted my Mac, but it made no difference. I looked at the Activity Monitor and couldn’t identify what was causing this, so I opened up the terminal and managed to figure it out pretty quickly using the following command:
sudo lsof +D /Volumes/Backup
This provided a list of all the different processes, and users, accessing that particular volume. I noticed that command “mds_store” with user “_mds_stores” was accessing the disk constantly in various directories. A quick search revealed that this is MacOS Spotlight indexing and cataloging files to speed up search. As the disk is just used as a backup target I decided to disable the indexing of the volume the following way:
- Open System Settings
- Go to Spotlight
- Scroll down to “Search Privacy…”
- Click “+” to add the volume you want to exclude from being indexed and click Done
Within seconds, literally, the rattling stopped and I regained my sanity.