What Is mds_stores? Fixing High CPU on a Mac
Your Mac is warm, the fans are up, and Activity Monitor shows a process called mds_stores near the top of the CPU list. You did not start it and you cannot tell what it is doing.
The short answer: mds_stores is the part of Spotlight that keeps the search index on disk. It gets busy when there is a lot to index, typically after a macOS update, a migration to a new Mac, or a large copy of files, and it settles when the work is done. If it stays busy for days, find what Spotlight keeps reindexing and exclude it, or rebuild the index.
What mds_stores does
Spotlight is made of three kinds of process:
| Process | What it does | Runs as, on our test Mac |
|---|---|---|
mds |
The metadata server: decides what to index and answers searches | root |
mds_stores |
Keeps the index itself on disk | _mds_stores |
mdworker_shared |
The workers that open files and read their contents | Your account, and _spotlight |
Apple's manual page describes mds as "the metadata server" that "serves all clients of the metadata APIs, including Spotlight." mds_stores is started by macOS as the job com.apple.metadata.mds.index, and on our test Mac, running macOS 27.0.1, it ran under its own system account, _mds_stores.
When files change, the workers read them and mds_stores writes what they found into the index. That writing, sorting and merging is the CPU and disk activity you see.
Why it is using so much CPU
mds_stores works hardest when a lot changes at once:
- A new Mac or a migration. The whole drive has to be indexed from scratch.
- A macOS update. Spotlight often has to update its index afterwards.
- A large copy. Hundreds of gigabytes of photos, video or documents arriving at once.
- A new external drive. Spotlight indexes other volumes too, unless told not to.
- Folders that change constantly, such as build output, caches or virtual machine images, which keep the index busy all the time.
macOS starts it with low background priority for disk access (LowPriorityBackgroundIO in its launch configuration), so it is designed to yield to what you are doing. A busy mds_stores is usually a sign of a lot of indexing, not of a fault.
The workers that do the reading often show up alongside it. Our guide to mdworker_shared covers them, including how to find the exact file Spotlight is stuck on.
How to fix mds_stores high CPU
1. Let it finish
After an update, a migration or a big copy, leave the Mac on and plugged in. A full index of a large drive can take hours. When it is done, mds_stores drops back to almost nothing. On our test Mac, idle after more than a day of uptime, it was using 0.2% of CPU.
2. Exclude what does not need to be searchable
Folders that change all the time and that you never search for are the most common reason indexing never ends.
- If System Settings has a separate Spotlight pane (as on macOS 27): open System Settings > Spotlight, click Search Privacy…, click + and choose the folder or disk.
- If it has Siri & Spotlight instead: the same list is under System Settings > Siri & Spotlight > Spotlight Privacy.
Be selective: macOS warns that search will not work in some applications for anything you exclude.
3. Rebuild the index if it has been stuck for days
If mds_stores has been busy for days and nothing above helped, the index may be damaged. Erase and rebuild it from Terminal:
sudo mdutil -E /Expect Spotlight to be busy for hours afterwards while it rebuilds, and search results to be incomplete until then. To check that indexing is switched on at all, run mdutil -s /, which answers Indexing enabled. when it is.
Can you quit it?
Do not bother. mds_stores belongs to a system account and is part of how Spotlight works, so macOS needs it running. Quitting it does not remove the indexing work that made it busy.
Keep an eye on it
MacStats keeps CPU, memory and the busiest processes one click away in the menu bar, so a long indexing run is easy to spot. It lists processes running under your own account, such as the mdworker_shared workers, and with MacStats Pro you can click one for a plain-English explanation. mds_stores itself runs under its own system account, which MacStats does not list yet.
macOS reports normal memory pressure.
↓8.03KB Live Activity
- 1MacStats16.4%›
- 2corespotlightd7.3%›
- 3Siri AI6.5%›
- 4dataaccessd2.3%›
- 1Google Chrome486.2 MB›
- 2Chrome Helper380 MB›
- 3OrbStack Helper373.6 MB›
- 4cmux296.7 MB›
MacBook Air, Apple M4 | 16 GB RAM | macOS 27.0
See what is keeping your Mac busy before the fans tell you.
Frequently asked questions
What is mds_stores on a Mac?
It is the part of Spotlight that keeps the search index on disk. The workers read your files, and mds_stores stores what they found so Spotlight can search it.
Is mds_stores a virus?
No. It is part of macOS, started as the job com.apple.metadata.mds.index from the system Metadata framework, and it runs under its own system account, _mds_stores.
How long does mds_stores take to finish indexing?
It depends on how much has changed. A small update can take minutes; indexing a whole drive after a migration can take hours. Leave the Mac on and plugged in until it settles.
Can I force quit mds_stores?
It does not help. It is a system process that Spotlight needs, and quitting it does not remove the indexing work that made it busy. Exclude folders you never search, or rebuild the index with sudo mdutil -E / if it has been stuck for days.
How do I stop mds_stores using so much CPU?
Let indexing finish first. If it never settles, exclude constantly changing folders in Spotlight's Search Privacy settings, and as a last resort rebuild the index with sudo mdutil -E /.