Safe to Quit
Time Machine · macOS process

backupd on Mac: Time Machine's engine, why it is busy, and how long it takes

backupd is Time Machine. When it shows up in Activity Monitor, a backup is running: the hourly one to your backup disk, or a local snapshot on the Mac itself. It reads every changed file, so it is busy after a macOS update, a big download or a Photos import, and the very first backup to a new disk can take hours. It stops on its own when the backup finishes. Do not quit it mid-backup; if you need the Mac quiet, click the Time Machine icon in the menu bar and choose Skip This Backup instead.

Let it finishIt is doing a job and stops on its own. Quitting it only makes it start over.

Updated 12 November 2026 · macOS 12 Monterey to macOS 26 Tahoe · 5 min read

What it is
The Time Machine backup daemon. It copies changed files to your backup disk and keeps the hourly local snapshots on the Mac.
Normal
20 to 80 percent CPU and steady disk activity for a few minutes every hour, longer after big changes. Hours for a first backup.
Not normal
Busy all day with no new files, a backup that never reaches 100 percent, or "Preparing backup" for hours on end.
Safe to quit?
Not from Activity Monitor. Use Skip This Backup in the Time Machine menu; backupd stops cleanly and tries again later.
The one safe fix
Let it finish on power. If it never does, check the backup disk in Time Machine settings and run First Aid on it in Disk Utility.

What backupd does

backupd is the daemon behind Time Machine. Every hour, when a backup disk is connected (or reachable over the network), the system wakes it to look for files that changed since the last backup, copy them across, and link the unchanged ones so each hourly backup looks like a complete copy without using the space of one. Between backups it also creates the local snapshots that let you restore a file from this morning even when the backup disk is at home. Those snapshots are what the Time Machine local snapshots page is about.

A backup has phases, and the phase explains the CPU. First comes "Preparing backup," where backupd compares the file system event log against the last backup to work out what changed; on a Mac with millions of files this alone can take a while. Then comes the copy, which is mostly disk work with modest CPU. Finally it thins old backups and old snapshots to make room, which is quick on an SSD and slow on a spinning disk. Then it exits, and the name disappears from Activity Monitor until the next hour.

Because it touches so many files, backupd also drags other processes along: the Spotlight indexer may wake to index the backup, and diskarbitrationd handles the disk appearing and disappearing. Seeing them together is normal.

What normal looks like

Time Machine's workload is driven entirely by how much changed since the last run. The same Mac can finish in two minutes one hour and take all evening the next:

Hourly backup, quiet dayA few minutes, 10 to 30 percentA handful of changed documents, mail and caches. You will rarely notice it.
After a big import or download20 to 60 minutes, 30 to 70 percentTens of gigabytes of photos or video have to be copied. Longer over Wi-Fi.
After a macOS updateOne to several hoursThe system volume changed, so a large chunk is re-read and re-linked.
First backup to a new diskHours, sometimes overnightEverything is copied once. Normal. Leave the Mac on power and awake.
How long backupd runs by what changed. Durations from the Safe to Quit knowledge base and Apple's Time Machine guidance; the first backup is always the big one.

The other thing people notice is that the backup disk stays busy for a while after Time Machine says the backup is done. An Apple Community poster asked exactly this in 2021 and the best answer was that the Mac is indexing the new files on the backup disk, which is Spotlight, not backupd. Give it a minute before ejecting.

Why backupd is using CPU right now

If backupd is at the top of the CPU list, one of these is true:

  1. A backup is simply running. Click the Time Machine icon in the menu bar; it shows the progress. If the number is moving, this is normal and the only question is how long to wait.
  2. A lot just changed. A macOS update, a Photos library import, a large download, a virtual machine disk or a big project folder that rewrites itself. Each of those is a lot of new data to copy.
  3. It is the first backup. A new disk, a new Mac, or Time Machine turned back on after being off for months. The first run copies everything.
  4. The backup disk is slow or far away. A spinning disk over USB 2, or a network share over Wi-Fi, keeps backupd waiting and working for far longer than an SSD on a cable would.
  5. The disk has a problem. If the backup keeps failing and restarting, or stays on "Preparing backup" for hours every time, the backup volume may need First Aid, or the disk is failing. This is the case that does not fix itself.

One thing it is not: a sign that something is wrong with the Mac. backupd working hard is the Mac doing exactly what you asked when you turned Time Machine on.

Is it safe to quit backupd?

Force quitting backupd from Activity Monitor will not damage your Mac, but it can leave a half-finished backup that Time Machine has to clean up next time, which makes the next run longer. There is a better button for the same job. Click the Time Machine icon in the menu bar (or open System Settings, General, Time Machine) and choose Skip This Backup. backupd stops cleanly within a few seconds and Time Machine tries again at the next hour. If you need silence for longer, turn off Back Up Automatically for the afternoon and turn it back on later.

What you should not do is stop a backup over and over because it keeps looking busy. Each interrupted run has to be redone, so the Mac never catches up and you never get a current backup. If you keep wanting to stop it, the real fix is a faster disk or a wired connection.

What are you about to quit?

Type any process name above to see whether it is one that finishes on its own, like backupd, or one you should leave alone entirely.

What to do, in order

  1. Check the progress

    Click the Time Machine icon in the menu bar. If it shows gigabytes copied and the number is climbing, a backup is running normally. Leave it. If you do not see the icon, turn on Show Time Machine in Menu Bar in Control Center settings.

  2. Plug in and stay awake

    On battery, macOS slows background work and may pause the backup. Connect power and keep the Mac awake for the first backup or a big one. Backups also pause when the lid is closed unless the Mac is on power and connected to a display.

  3. Use a cable for the big one

    If the backup disk is a network drive or the Mac is on Wi-Fi, do the first backup or a large one over a cable if you can. Hours become minutes.

  4. Skip it if you need the Mac now

    Choose Skip This Backup from the Time Machine menu and let it run later. This is the right way to stop backupd.

  5. Check the disk if it never finishes

    If Time Machine shows "Preparing backup" for hours every time, or the backup fails repeatedly, open Disk Utility, select the backup volume and run First Aid. If First Aid reports errors it cannot fix, the disk is the problem, and a new backup disk is the fix.

When to worry

The only real risk with backupd is the opposite of the one people fear: not that it runs too much, but that it quietly stops working and you find out when you need a restore. Use time as the test:

  1. A few minutes each hourNormal hourly backup. Nothing to do.
  2. An hour or twoAfter an update or a big import, or the first backup over Wi-Fi. Still normal. Leave it on power.
  3. OvernightFirst backup to a new disk, or a very large Photos library. Normal once. Not normal if it happens every night.
  4. Days, never finishingThe backup is failing and restarting. Run First Aid on the backup disk; replace it if errors persist.
How long a Time Machine backup is allowed to take before it counts as stuck.

Also check the date of the last successful backup in Time Machine settings now and then. If it is more than a day old while the disk is connected, backupd is not the problem; the backup is. That is where Safe to Quit's "settles on its own" verdict matters: it tells you whether a busy process is finishing or looping.

What people hit, in their words

“Why does the external drive continue to show disk activity after a time machine backup is complete?”

“My belief is that this is the computer indexing the backup drive since some new or changed files have been placed on it.”

Apple's own walkthrough of setting up the backup that backupd runs

How to back up your Mac with Time Machine | Apple Support by Apple Support. Covers choosing a disk and the first backup. It does not mention backupd by name; everything it shows is what the daemon does in the background.

Questions people ask

What is backupd on my Mac?

backupd is the background process that performs Time Machine backups. When Time Machine runs its hourly backup, or creates a local snapshot, backupd is the name you see in Activity Monitor doing the reading, copying and cleanup. It only appears while a backup is in progress and exits when the backup is finished, so it is often absent from the list entirely.

Why does my Time Machine backup keep failing?

The usual causes are a backup disk with file system errors, a disk that is nearly full and cannot thin old backups fast enough, a network share that drops during the copy, or the Mac sleeping mid-backup on battery. Run First Aid on the backup volume in Disk Utility, free space or use a bigger disk, keep the Mac on power, and prefer a cable for large backups.

How long should a Time Machine backup take?

The first backup copies everything and can take several hours, overnight for a large library or over Wi-Fi. After that, hourly backups copy only what changed and usually finish in a few minutes. A backup after a macOS update or a big import sits in between, often an hour or two. If every backup takes hours, the disk or the connection is too slow.

What files does Time Machine not back up?

Time Machine skips caches, temporary files, the swap and sleep images, the Trash, and anything you add to the exclusion list in Time Machine settings under Options. It also skips most of the sealed macOS system volume, which is restored from the installer rather than from backup. Your documents, photos, mail, apps and settings are all included by default.

Can I stop backupd?

Yes, but use the Time Machine menu rather than Activity Monitor. Choose Skip This Backup and backupd stops cleanly, then tries again at the next hour. Force quitting it leaves a partial backup to clean up and makes the next run slower. To pause for longer, turn off Back Up Automatically in Time Machine settings and turn it back on later.

Sources and further reading