What is mds_stores on Mac?
mds_stores writes Spotlight’s search index. A burst of CPU and disk activity after a macOS update or a big file copy is normal. Hours of it, every day, usually means it’s indexing something you never search.
Updated
- Process
mds_stores- Comes from
- macOS
- Safe?
- Safe. Part of Spotlight. You can quit it, but it restarts; exclude folders instead.
What mds_stores does
Spotlight is three kinds of processes working together. mds receives notice that files changed, mdworker_shared reads each file and extracts text and metadata, and mds_stores writes all of it into the index database stored in /.Spotlight-V100 on each volume. When you see mds_stores busy, it’s storing and compacting that index.
The binary lives in /System/Library/Frameworks/CoreServices.framework/.../Metadata.framework/Versions/A/Support/mds_stores and runs as root.
Why it uses CPU and disk
- A macOS update: major and minor updates often trigger a full reindex. Expect a busy first hour.
- A new or reconnected drive: external SSDs get indexed the first time they mount.
- Large copies or restores: migrating from another Mac, restoring a backup, unzipping archives.
- Developer folders:
node_modules,.gitobjects, XcodeDerivedData,~/Library/Caches, Docker and VM disk images. A singlenpm installcan create 50,000 files that Spotlight then reads. - A damaged index: mds_stores at high CPU for days, with search results missing, usually means the index is corrupt.
How to make it calm down
Check indexing status for your volumes:
mdutil -s /
mdutil -s /Volumes/YourDrive
Exclude folders you never search: System Settings › Spotlight › Search Privacy (on Sonoma it’s Siri & Spotlight › Spotlight Privacy). Drag in your code folder, ~/Library/Developer, VM folders and any backup drives. Excluded folders are removed from the index.
Turn indexing off for a specific external drive:
sudo mdutil -i off /Volumes/YourDrive
If the index looks broken, rebuild it (takes a while, search is incomplete until done):
sudo mdutil -E /
To see which files are being read right now:
sudo fs_usage -w -f filesys mdworker_shared | head -50
When to worry
The real mds_stores runs as root from inside CoreServices. Check:
ps -o user,pid,command -p $(pgrep -x mds_stores)
Anything named mds_stores in your home folder or /Library/Application Support is not Spotlight. Otherwise, the only real worry is an index that never finishes. If rebuilding twice doesn’t settle it, an app is probably writing files in a loop; fseventsd activity and fs_usage will show which.
Seeing it in Stat Space
In Stat Space’s Apps tab, mds, mds_stores and the mdworker_shared processes sit in the System group with their CPU and memory, and its process dictionary explains each in a line (statspace whatis mds_stores in Terminal). The disk module shows read and write throughput in the menu bar, so you can tell whether an indexing burst is what’s making your Mac feel slow.
Questions
Can I turn off Spotlight indexing completely?
Yes, with sudo mdutil -a -i off, but Spotlight search, Mail search and many app searches stop working. Excluding busy folders is almost always the better trade.
How long does Spotlight reindexing take?
On an Apple Silicon Mac with a few hundred GB of files, usually 15 minutes to a couple of hours. Millions of small files (dependency folders, photo libraries) make it much longer.
What’s the difference between mds, mds_stores and mdworker?
mds is the coordinator, mdworker_shared processes read files and extract metadata, and mds_stores writes the results into the index on each volume.
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