mds_stores using high CPU on a Mac: Spotlight indexing, and when to step in
mds_stores is the Spotlight index. It spikes after updates and big copies, then settles: 0.1% on our Mac at rest. How to check it and what to exclude.
What is mds_stores?
Spotlight is three kinds of process working together. mds runs the show, mdworker_shared processes read files, and mds_stores writes what they find into the index. On our Mac it ran as its own user, _mds_stores, from the Metadata framework in CoreServices.
| Process | Runs as | At rest on our Mac |
|---|---|---|
mds | root | 0.0% CPU, 8 MB |
mds_stores | _mds_stores | 0.1% CPU, 15 to 23 MB |
mdworker_shared | you | several short lived copies, 0.0% |
Why is mds_stores using high CPU?
- After a macOS update, which often means rebuilding much of the index.
- After copying or unzipping many files at once, or restoring from a backup.
- With folders that change constantly:
node_modules, build output, virtual machine disks, mail with many small messages. - When an external drive is plugged in for the first time.
How do I check what Spotlight is doing?
mdutil -s /
sudo fs_usage -w -f filesys mds_stores | head -50The first says whether indexing is on; the second shows which files it is touching right now (stop it with Control C). If you see the same project folder over and over, that folder is the work.
How do I stop it indexing folders I do not need?
Open System Settings, Spotlight, Search Privacy, and add the folders: your projects' build folders, a virtual machines folder, a downloads archive. Spotlight stops indexing them and forgets what it had. For developers this is the biggest single saving; see Spotlight index taking up space.
Should I rebuild the index?
Only if search is broken, results are missing or stale for days. sudo mdutil -E / erases and rebuilds it, which itself means hours of mds_stores at high CPU.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also mdworker_shared and the CoreSpotlight folder.
Related: mdworker_shared and coreaudiod.
Common questions
What is mds_stores on a Mac?
The Spotlight process that writes the search index. It works with mds and mdworker_shared.
Why is mds_stores using so much CPU?
Spotlight is indexing, usually after an update, a big copy or files that change constantly. It settles once it catches up.
How do I stop Spotlight indexing a folder?
System Settings, Spotlight, Search Privacy, then add the folder.