# Time Machine (macOS)

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macOS backup software application

Time Machine Time Machine's retrieval interface on macOS 11 Developer Apple Operating system macOS 10.5 or newer Type Backup software License Proprietary Website support.apple.com/en-us/HT201250

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**Time Machine** is the [backup](/source/Backup_software) mechanism of [macOS](/source/MacOS), the desktop [operating system](/source/Operating_system) developed by [Apple](/source/Apple_Inc.). The software is designed to work with both local storage devices and network-attached disks, and is commonly used with external disk drives connected using either [USB](/source/USB) or [Thunderbolt](/source/Thunderbolt_(interface)). It was introduced in [Mac OS X 10.5 Leopard](/source/Mac_OS_X_Leopard), which was released in October 2007 and incrementally refined in subsequent releases of macOS. Time Machine was revamped in [macOS 11 Big Sur](/source/MacOS_Big_Sur) to support [APFS](/source/Apple_File_System), which enabled faster and more reliable backups.[1][2]

## Overview

Time Machine creates incremental backups of files that can be restored at a later date.[3] It allows the user to restore the whole system or specific files. It also works within a number of applications such as [Mail](/source/Apple_Mail) and [iWork](/source/IWork), making it possible to restore individual objects (e.g. emails, contacts, text documents, presentations) without leaving the application.

Time Machine saves hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for everything older than a month until the volume runs out of space. At that point, Time Machine deletes the oldest weekly backup.[4]

For backups to a network drive, Time Machine allows the user to back up Mac computers over the network, and supports backing up to certain [network attached storage](/source/Network-attached_storage) devices or servers, depending on the version of Time Machine. Earlier versions worked with a wide variety of NAS servers, but later versions required the server to support a recent version of Apple's [Apple Filing Protocol (AFP)](/source/Apple_Filing_Protocol) or a recent version of the [Server Message Block (SMB)](/source/Server_Message_Block) protocol, and Time Machine no longer works with servers using earlier versions of SMB.[5] Some of the legacy support can be re-enabled by using hand-tuned configuration options, accessed through the [Terminal](/source/Terminal_(macOS)). Apple's [AirPort Time Capsule](/source/AirPort_Time_Capsule) router, which was introduced in 2008 and discontinued in 2018, acted as a [network storage](/source/Network-attached_storage) device specifically for Time Machine backups, allowing both wired and wireless backups to the Time Capsule's internal hard drive. Time Machine may also be used with other external or internal volumes.

[macOS Tahoe](/source/MacOS_Tahoe) will be the last version of macOS to support AFP, with macOS 27 onward only supporting Time Machine backups over SMB version 2 or later. Time Machine backups using AirPort Time Capsule routers will no longer function.[6]

## Revamp in macOS Big Sur

Time Machine was overhauled in [macOS 11 Big Sur](/source/MacOS_Big_Sur) to utilize [APFS](/source/APFS), Apple's modern [file system](/source/File_system) introduced in 2016, and makes use of APFS's [snapshot](/source/Snapshot_(computer_storage)) technology.[1][7][8] According to Apple, this enables "faster, more compact, and more reliable backups" than were possible previously with [HFS+](/source/HFS_Plus)-formatted drives.[1][2] An independent evaluation of this claim found that macOS 11's Time Machine implementation in conjunction with APFS was 2.75-fold faster upon initial local backup and 4-fold faster upon subsequent backups relative to macOS 10.15's Time Machine implementation using HFS+.[2] A more modest yet nevertheless significant advantage was noted as well for backups to network-attached disks.[2]

Local (i.e. USB- or Thunderbolt-connected) and network-connected Time Machine backup destinations are formatted as APFS by default, though Time Machine can continue backing up to existing HFS+ backup volumes."[1] There is no option to convert existing, HFS+-based backups to APFS; instead, users who want to benefit from the advantages of the new, APFS-based implementation of Time Machine need to start with a fresh volume.[2]

At least in some circumstances, encryption appears to be required (instead of merely optional) in the new version of Time Machine.[2]

## User interface

Time Machine's [user interface](/source/User_interface) when retrieving a file uses Apple's [Core Animation](/source/Core_Animation) [API](/source/Application_programming_interface). Upon its launch, Time Machine "floats" the active [Finder](/source/Finder_(software)) or application window from the user's desktop to a backdrop depicting the user's blurred desktop wallpaper. Behind the current [active window](/source/Active_window) are stacked windows, with each window representing a [snapshot](/source/Snapshot_(computer_storage)) of how that folder or application looked on the given date and time in the past. When toggling through the previous snapshots, the stacked windows extend backwards, giving the impression of flying through a "time tunnel." While paging through these "windows from the past", a previous version of the data (or currently deleted data) may be retrieved.

## Storage

Time Machine works with locally connected storage disks, which must be formatted in the [APFS](/source/Apple_File_System) or [HFS+](/source/HFS_Plus) volume formats. Support for backing up to APFS volumes was added with [macOS 11 Big Sur](/source/MacOS_Big_Sur) and since then APFS is the default volume format.

Time Machine also works with remote storage media shared from other systems, including Time Capsule, via the network. When using remote storage, Time Machine uses [sparse bundles](/source/Sparse_image). This acts as an isolation layer, which makes the storage neutral to the actual file system used by the network server, and also permits the replication of the backup from one storage medium to another. Sparse bundles are mounted by macOS like any other device, presenting their content as a HFS+ formatted volume, functionally similar to a local storage.

### Requirements

Time Machine places strict requirements on the backup storage medium. The only officially supported configurations are:[9]

- A storage drive or partition connected directly to the computer, either internally or by a bus like [USB](/source/USB) or [Thunderbolt](/source/Thunderbolt_(interface)) and formatted as [APFS](/source/Apple_File_System) or [journaled](/source/Journaling_file_system) [HFS+](/source/HFS_Plus). If the volume format is not correct, Time Machine will prompt the user to reformat it.

- A folder on another Mac on the same network.

- The internal drive of an Apple [AirPort Time Capsule](/source/AirPort_Time_Capsule) router on the same network, or a USB drive connected to an AirPort Time Capsule 802.11ac or [AirPort Extreme](/source/AirPort_Extreme) 802.11ac router on the same network. (USB hard drives on earlier generations of the AirPort Extreme/Time Capsule are not supported.) *(This option is only supported in [macOS Tahoe](/source/MacOS_Tahoe) and earlier and will be dropped with macOS 27.)*[6]

- Local network volumes connected using the [Apple Filing Protocol](/source/Apple_Filing_Protocol) (supported through macOS Tahoe) or via an [SMB3](/source/Server_Message_Block#SMB_3.0) share that advertises a number of capabilities.[5]

On a Time Capsule, the backup data is stored in an HFS+ [disk image](/source/Disk_image) and accessed via [Apple Filing Protocol](/source/Apple_Filing_Protocol). Although it is not officially supported, users and manufacturers have also configured [FreeBSD](/source/FreeBSD) and [Linux](/source/Linux) servers and [network-attached storage](/source/Network-attached_storage) systems to serve Time Machine-enabled Macs. There are also a few software tools available on the market that can copy files inside Time Machine backups in Windows machines.[10][11][12][13][14][15][16] [17]

## Operation

Time Machine creates a folder on the designated Time Machine volume (local or inside a remote [sparse image](/source/Sparse_image)) into which it copies the directory tree of all locally attached storage drives, except for files and directories that the user has specified to omit, including the Time Machine volume itself. Every hour thereafter, it creates a new subordinate folder and copies only files that have changed since the last backup and creates (in the case of HFS+ volumes) [hard links](/source/Hard_link) to files that already exist on the backup drive. A user can browse the directory hierarchy of these copies as if browsing the primary disk.[18]

Some other backup utilities save deltas for file changes, much like [version control](/source/Version_control) systems. Such an approach permits more frequent backups of minor changes, but can often complicate the interaction with the backup volume. By contrast, it is possible to manually browse a Time Machine backup volume without using the Time Machine interface; Time Machine presents each backup to the user as a complete disk copy.[18]

Time Machine on HFS+ volumes creates multiple hard links to unmodified directories.[18] Multiple linking of directories is a peculiar feature for HFS+, and is not supported on modern Unix file systems including Apple's own APFS.[19] As a result, tools like [rsync](/source/Rsync) cannot be used to replicate a Time Machine volume; replication can only reliably be done by imaging the entire filesystem.

Apple system events record when each directory is modified on the hard drive. This means that instead of examining every file's modification date when it is activated, Time Machine only needs to scan the directories that changed for files to copy. This differs from the approach taken by similar backup utilities [rsync](/source/Rsync) and [FlyBack](/source/FlyBack), which examine modification dates of all files during backup.

Time Machine is also available in the [macOS](/source/MacOS) installation process. One of the features in the [Migration Assistant](/source/Migration_Assistant_(Apple)) interface is to restore the contents of a Time Machine backup. In other words, a hard drive can be restored from a Time Machine backup in the event of a catastrophic crash.

[OS X Mountain Lion](/source/OS_X_Mountain_Lion) introduced the ability to use multiple volumes simultaneously for Time Machine operations. When the user specifies more than one volume to use, macOS rotates among the desired volumes each time it does a backup.[20]

## Exclusion

Time Machine supports two forms of exclusion: one based on a user-configured list of paths (plus a set of system defaults), the other based on the [extended file attribute](/source/Extended_file_attributes) com.apple.metadata:com_apple_backup_excludeItem dependencies. Since the attribute is applied to the file or directory directly, moving or copying will not affect the exclusion. The attribute should contain the string com.apple.backup in any [property list](/source/Property_list) format. Writing com.apple.MobileBackup instead sets the exclusion for iOS backups.[21]

Google Chrome is known to use the attribute to exclude its histories.[21] Third-party backup applications that respect this setting include CrashPlan and Arq.[22] Apple wraps the attribute into the tmutil command-line utility[21] as well as a CoreServices API.[23]

## See also

- [MobileMe Backup](/source/Backup_(backup_software))

- [List of backup software](/source/List_of_backup_software)

- Backup options built into Microsoft Windows: [System Restore](/source/System_Restore), [File History](/source/Features_new_to_Windows_8#File_History)

## References

1. ^ [***a***](#cite_ref-macOS_11.0.1_Release_Notes_(Apple)_1-0) [***b***](#cite_ref-macOS_11.0.1_Release_Notes_(Apple)_1-1) [***c***](#cite_ref-macOS_11.0.1_Release_Notes_(Apple)_1-2) [***d***](#cite_ref-macOS_11.0.1_Release_Notes_(Apple)_1-3) ["macOS Big Sur 11.0.1 Release Notes"](https://developer.apple.com/documentation/macos-release-notes/macos-big-sur-11_0_1-release-notes). *Apple*. Retrieved December 13, 2020.

1. ^ [***a***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-0) [***b***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-1) [***c***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-2) [***d***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-3) [***e***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-4) [***f***](#cite_ref-Ars_Technica_2020.11.12,_macOS_Big_Sur_Review_2-5) Cunningham, Andrew (November 12, 2022). ["macOS 11.0 Big Sur: The Ars Technica review"](https://arstechnica.com/gadgets/2020/11/macos-11-0-big-sur-the-ars-technica-review/). Ars Technica. Retrieved March 6, 2021.

1. **[^](#cite_ref-apple_tm_3-0)** Apple. ["Apple - Mac OS X Leopard - Features - Time Machine"](https://www.apple.com/macosx/features/timemachine.html). Retrieved December 21, 2007.

1. **[^](#cite_ref-4)** Tiwari, Saurabh (May 7, 2018). ["Create a backup with Time Machine on Mac"](https://techibhai.com/create-backup-time-machine-mac/). *Techi Bhai*. Retrieved February 16, 2022.

1. ^ [***a***](#cite_ref-AppleTimeMachineOverSMB_5-0) [***b***](#cite_ref-AppleTimeMachineOverSMB_5-1) ["Time Machine over SMB Specification"](https://developer.apple.com/library/archive/releasenotes/NetworkingInternetWeb/Time_Machine_SMB_Spec/). *Documentation Archive*. Apple Inc. September 13, 2016. Retrieved April 24, 2019.

1. ^ [***a***](#cite_ref-:0_6-0) [***b***](#cite_ref-:0_6-1) ["Warning: Apple Says macOS 27 Won't Support AirPort Time Capsule Backups"](https://www.macrumors.com/2025/06/10/macos-27-wont-support-airport-time-capsule/). *MacRumors*. June 10, 2025. Retrieved June 22, 2025.

1. **[^](#cite_ref-Owen,_Apple_Insider_2020.06.27_7-0)** Owen, Malcolm (June 27, 2020). ["APFS changes affect Time Machine in macOS Big Sur, encrypted drives in iOS 14"](https://appleinsider.com/articles/20/06/27/apfs-changes-affect-time-machine-in-macos-big-sur-encrypted-drives-in-ios-14). Apple Insider. Retrieved August 6, 2020.

1. **[^](#cite_ref-Oakley,_Eclectic_Light_Company_2020.06.20_8-0)** Oakley, Howard (June 20, 2020). ["APFS changes in Big Sur: how Time Machine backs up to APFS, and more"](https://eclecticlight.co/2020/06/29/apfs-changes-in-big-sur-how-time-machine-backs-up-to-apfs-and-more/). The Eclectic Light Company. Retrieved August 6, 2020.

1. **[^](#cite_ref-9)** ["Backup disks you can use with Time Machine"](https://support.apple.com/en-us/HT202784). *Apple Support*. Apple Inc. Retrieved November 30, 2020.

1. **[^](#cite_ref-10)** Matthias Kretschmann (June 19, 2008). ["HowTo: Make Ubuntu A Perfect Mac File Server And Time Machine Volume"](https://www.kremalicious.com/2008/06/ubuntu-as-mac-file-server-and-time-machine-volume). Retrieved September 11, 2009.

1. **[^](#cite_ref-11)** MKurtz. ["NSLU2-Linux - HowTo / TimeMachineBackups"](http://www.nslu2-linux.org/wiki/HowTo/TimeMachineBackups). Retrieved September 11, 2009.

1. **[^](#cite_ref-12)** harryd71 (November 23, 2009). ["Mac OS X Time Machine and FreeNAS 0.7"](https://harryd71.blogspot.com/2009/11/mac-osx-time-machine-and-freenas-07.html). Retrieved January 17, 2010.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: numeric names: authors list ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_numeric_names:_authors_list))

1. **[^](#cite_ref-13)** QNAP Systems Inc. ["QNAP NAS support for Apple Time Machine"](https://www.qnap.com/en-us/how-to/tutorial/article/using-time-machine-to-back-up-your-mac-to-a-qnap-nas-via-smb/). Retrieved November 30, 2020.

1. **[^](#cite_ref-14)** Bastian Bechtold. ["Using a Raspberry Pi as a Time Capsule for Mountain Lion"](http://bastibe.de/2012-07-29-using-raspberry-pi-as-time-machine.html). Retrieved August 23, 2012.

1. **[^](#cite_ref-alonso20130506_15-0)** Alonso, Noel. ["Using Netatalk: AFP Services on a Linux Server"](https://www.afp548.com/2013/05/06/afp-services-on-a-linux-server/). AFP548.com. Retrieved November 1, 2013. Also see slowfranklin's comment and its replies. To add the guest UAM, add AFPD_UAMLIST="-U uams_guest.so" to the [Global] section in afp.conf.

1. **[^](#cite_ref-16)** Bas van de Wiel. ["Ironclad Time Machine backups on FreeBSD"](http://www.area536.com/projects/ironclad-time-machine-backups-on-freebsd/). Retrieved March 18, 2016.

1. **[^](#cite_ref-17)** Amar Ilindra (November 21, 2018). ["How to Access and Restore Time Machine Backup Files on Windows"](https://www.geekdashboard.com/restore-time-machine-backups-windows/).

1. ^ [***a***](#cite_ref-PondHowTimeMachineWorks_18-0) [***b***](#cite_ref-PondHowTimeMachineWorks_18-1) [***c***](#cite_ref-PondHowTimeMachineWorks_18-2) Pond, James (August 31, 2013). ["How Time Machine Works its Magic"](https://web.archive.org/web/20190621092705/https://www.baligu.com/pondini/TM/Works.html). *Apple OSX and Time Machine Tips*. baligu.com. File System Event Store, Hard Links. Archived from [the original](http://pondini.org.ftp83plus.net/TM/Works.html) on June 21, 2019. Retrieved May 19, 2019.

1. **[^](#cite_ref-MacObserverTimeMachineAPFS_19-0)** Butts, Jeff (September 25, 2017). ["Time Machine and APFS: What You Need to Know"](https://www.macobserver.com/tips/deep-dive/time-machine-and-apfs-need-know/). *The Mac Observer*. Retrieved April 23, 2019.

1. **[^](#cite_ref-20)** Caldwell, Serenity (February 21, 2012). ["Ten exciting system changes in Mountain Lion"](http://www.macworld.com/article/1165496/ten_exciting_system_changes_in_mountain_lion.html). Mac-world. Retrieved April 29, 2012.

1. ^ [***a***](#cite_ref-bob_21-0) [***b***](#cite_ref-bob_21-1) [***c***](#cite_ref-bob_21-2) Bobby, Brant. ["macos - On OS X, what files are excluded by rule from a Time Machine backup?"](https://apple.stackexchange.com/a/25833). *Ask Different*.

1. **[^](#cite_ref-22)** ["Feature Request: Honor com_apple_backup_excludeItem on MacOS · Issue #478 · gilbertchen/duplicacy"](https://github.com/gilbertchen/duplicacy/issues/478). *GitHub*.

1. **[^](#cite_ref-23)** ["CSBackupSetItemExcluded - Core Services"](https://developer.apple.com/documentation/coreservices/1445043-csbackupsetitemexcluded?language=objc). *Apple Developers Documentation*.

## External links

- [Apple Support: Back up your Mac with Time Machine](https://support.apple.com/en-us/HT201250)

- [Mac OS X 10.5 Leopard review on Ars Technica](https://arstechnica.com/apple/reviews/2007/10/mac-os-x-10-5.ars/14)

- [brief history of Time Machine and its evolution to using APFS](https://eclecticlight.co/2021/03/04/time-machine-to-apfs-evolution/), by Howard Oakley

v t e macOS History Architecture Built-in apps Server Software Versions Mac OS X Server 1.0 Public Beta 10.0 Cheetah 10.1 Puma 10.2 Jaguar 10.3 Panther 10.4 Tiger 10.5 Leopard 10.6 Snow Leopard OS X 10.7 Lion 10.8 Mountain Lion 10.9 Mavericks 10.10 Yosemite 10.11 El Capitan macOS 10.12 Sierra 10.13 High Sierra 10.14 Mojave 10.15 Catalina 11 Big Sur 12 Monterey 13 Ventura 14 Sonoma 15 Sequoia 26 Tahoe 27 Golden Gate Predecessors Classic Mac OS NeXTSTEP Rhapsody Applications Core applications App Store Automator Calculator Calendar Contacts Control Center Dictionary FaceTime Finder Game Center Grapher Home Mail Messages News Music Notes Notification Center Podcasts Photo Booth Photos Preview QuickTime Player Reminders Safari Shortcuts Siri Stickies TextEdit Time Machine Developer Tools Xcode Instruments Former Interface Builder Dashcode Quartz Composer Utilities Boot Camp (deprecated) ColorSync Configurator Disk Utility Font Book Keychain Access Script Editor System Settings Terminal VoiceOver Former Dashboard Front Row iChat iPhoto iSync iTunes history Sherlock Technologies, user interface AirDrop AppKit Apple File System Apple menu Apple Push Notification service AppleScript Aqua Audio Units AVFoundation Bonjour Bundle CloudKit Cocoa ColorSync Command key Core Animation Core Audio Core Data Core Foundation Core Image Core OpenGL Core Text Core Video Cover Flow CUPS Darwin Dock FileVault Fonts Foundation Gatekeeper Grand Central Dispatch icns iCloud Kernel panic Keychain launchd Liquid Glass Mach-O Menu extra Metal Mission Control Night Shift OpenCL Option key Preference Pane Property list Quartz Quick Look Rosetta Smart Folders Speakable items Spotlight Stacks System Integrity Protection Uniform Type Identifier Universal binary WebKit XNU XQuartz Deprecated HFS+ Discontinued ATSUI BootX Brushed metal Carbon Classic Environment Inkwell QuickTime Spaces Xgrid Category

v t e Backup software and disk cloning software Active Acronis True Image Backblaze BorgBackup Carbon Copy Cloner Clonezilla Code42 dd Time Machine Category

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Adapted from the Wikipedia article [Time Machine (macOS)](https://en.wikipedia.org/wiki/Time_Machine_(macOS)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Time_Machine_(macOS)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.