What is mdsync on Mac?
Spotlight volume scan (mdsync) · seed · quit hint: caution
mdsync is a macOS process (listed here as Spotlight volume scan (mdsync)) — also matched as com.apple.Metadata. People usually find it in Activity Monitor when asking “what is this process?”
What does mdsync do?
mdsync is Spotlight’s volume scan worker (MDSSyncScanWorker in Metadata.framework). launchd starts it as com.apple.metadata.mds.scan so Spotlight can walk mounted volumes and keep the metadata index aligned with the filesystem. It is a sibling of mds, mds_stores, and mdworker. You need it while Spotlight is catching up after mounts or large file changes; quitting pauses that scan until relaunch. Prefer excluding noisy folders over force-quit.
When to leave mdsync running
- spotlight-in-use
Is it safe to quit mdsync?
Hint: caution. SystemWoe Free and Pro refuse to quit protected apps or Time Machine — Pro adds force-quit only with confirmation.
Further reading
- https://keith.github.io/xcode-man-pages/mds.8.html
- https://keith.github.io/xcode-man-pages/mdworker.8.html
- https://support.apple.com/guide/mac-help/mchlp1008/mac
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