The short answer
backupd runs Time Machine backups, with backupd-helper alongside it. It's busy while a backup runs, and busiest during the first backup or after lots of files changed. Check progress from the Time Machine menu in the menu bar or with tmutil status in Terminal, and let the backup finish. To make backups lighter, exclude big folders you don't need backed up in System Settings → General → Time Machine → Options. If you need to stop the current backup, skip it from the Time Machine menu or run tmutil stopbackup rather than quitting the process.
On this page
What backupd does
backupd is the Time Machine process. It works out what changed since the last backup, copies it to your backup disk, and removes the oldest backups when the disk fills. Apple says Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for all previous months.
backupd and backupd-helper are part of macOS and run from /System/Library/CoreServices/TimeMachine.
Why it's busy
- The first backup. Everything is copied. Apple notes it might take longer than you expect, and you can keep using the Mac meanwhile.
- Lots of changed files. A big download, a photo import, or a project folder that was rebuilt.
- Large files that change often. Virtual machine disks and container disk images are single large files that change all the time, so each backup has a lot to copy.
- A slow or network backup disk. The same backup simply takes longer, so backupd stays busy for longer.
- Spotlight on the backup disk. Apple notes that Spotlight indexes a Time Machine backup disk even if you exclude it, because Time Machine needs that index. You may see mds_stores busy at the same time.
How to check what it's doing
If you've added the Time Machine menu to the menu bar, it shows the backup in progress or the time of the latest one. For more detail, use Terminal:
tmutil statusBackup session status:
{
BackupPhase = Copying;
ClientID = "com.apple.backupd";
Percent = "0.42";
Running = 1;
}Running = 1 means a backup is in progress, BackupPhase says which stage it's in, and Percent how far through it is, as a fraction. Running = 0 means Time Machine is idle.
log show --last 1h --style compact --predicate 'subsystem == "com.apple.TimeMachine"' | tail -20Is it safe to quit backupd?
It quits and restarts itself. Quitting it stops the backup that's running, and Time Machine tries again later. Your earlier backups are untouched, but the progress is lost. If you need the Mac's full speed now, skip the backup from the Time Machine menu, or run tmutil stopbackup, instead of quitting the process.
How to make backups lighter
- Let the first backup finish, ideally with the Mac plugged in and the backup disk connected directly.
- Exclude what you don't need: open System Settings → General → Time Machine, click Options, click the add button (+) and choose the folders. Good candidates are virtual machine and container disk images, build folders and anything you can download or rebuild again.
- If backups run at a bad time, change Back up frequency in the same Options sheet.
tmutil isexcluded ~/DownloadsThe faster way: “What is this?” in iKnowMyMac
iKnowMyMac explains this inside the app. Every process row has a “What is this?” action that says what the process is, whether it's safe to quit, why it's busy right now and the one fix. For backupd, it says whether Time Machine is working right now.