Time Machine (macOS): Difference between revisions

Revision as of 16:28, 16 October 2014

Revision as of 03:59, 22 October 2014

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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.

==Mountain Lion / Mavericks Compatibility Issues==

{{POV-section|date=October 2014}}

Coding differences between OSX Mountain Lion and Mavericks have resulted in fundamental compatibility issues related to Time Machine system restoration functionality. Time Machine backups created by Apple computers purchased as recently as late 2012 cannot be used for system restoration on 2013 or 2014 models. The backups are readable only by the computer that created them and thus prompt an error message "backup was created by an older model." As a result, any unrepairable hard drive failure or "system crash" on a 2012 (or earlier) Apple computer leaves the Time Machine user vulnerable to massive data loss, unable to restore their operating system via Time Machine on a newer replacement computer using the backups from the disabled unit.{{Citation needed|date = April 2014}}

[This inaccurately suggests that users can't get to their data from older machines. More accurately, you can't install an older version of OS X on a newer Mac. You can use Migration Assistant to move all the data and all compatible applications from an older Time Machine backup to a newer Mac, or you can use Finder to retrieve your files from the older Time Machine backup. The only thing you can't do is "restore" an older version of OS X to a computer that was built with hardware that requires drivers that only exist in newer versions of OS X.]

==User interface==

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[[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, OS X rotates among the desired volumes each time it does a backup. <ref>{{cite web | url=http://www.macworld.com/article/1165496/ten_exciting_system_changes_in_mountain_lion.html | title=Ten exciting system changes in Mountain Lion | publisher=Macworld | date=February 21, 2012 | accessdate=April 29, 2012 | author=Caldwell, Serenity}}</ref>

Coding differences between OSXOS X Mountain Lion and Mavericks have resulted in fundamental compatibility issues related to Time Machine's system restoration functionality. Time Machine backups created by Apple computers purchased as recently as late 2012 cannot be used for system restoration on 2013 or 2014 models. {{Citation Theneeded|date backups= areOctober readable only by the computer that created them and thus prompt an error message "backup was created by an older model2014}}." As a resultHowever, any unrepairable hard drive failure or "system crash" on a 2012 (or earlier) Apple computer leaves the Time Machine user vulnerable to massive data loss,from unablethe tobackup restorecan theirstill operatingbe systemrecovered viaby Timedirectly Machine on a newer replacement computer usingaccessing the backupsfiles from the disabledTime unitMachine Volume.{{Citation needed|date = April 2014}}

==Requirements==