Time Machine is designed to again up your chosen volumes each hour, writing any modifications you’ve made into a brand new snapshot that captures solely the variations between the earlier backup. (Apple software program, like Pages and Numbers, and loads of third-party software program create a model each time you save, offering backups inside apps rather more ceaselessly than hourly.)
However some readers marvel what occurs in the event that they don’t maintain their Time Machine drives powered up on a regular basis. Apple designed Time Machine to be resilient, so it doesn’t skip a beat if a number of of the vacation spot volumes you utilize for backups isn’t at all times obtainable.
The perfect state of affairs is that any drive you utilize is at all times plugged in and thus backups at all times occur whereas it’s on. That is notably helpful—perhaps vital—in case your Mac acts as a networked Time Machine vacation spot for different computer systems on the community, as they could be backing up at occasions you’re not utilizing your Mac—if a companion is working late or considered one of your children is writing their time period paper at 2 a.m.
Nevertheless, so long as macOS allows you to unmount the Time Machine drive, it’s secure to not have it related. Use the Finder to pick out the drive and select File > Eject “drive identify” (Command-E), and macOS will inform you if it’s in use, or it should eject it in any other case. You may also shut down your Mac, and the drive will correctly unmount and be completely secure to energy down or unplug as soon as your Mac shuts down fully.
Whereas your drive (or drives) aren’t related, macOS makes use of short-term native Time Machine snapshots to retailer interim variations, so that you don’t lose modifications throughout that interval, both. (These can generally bloat out of the management for unknown causes; right here’s some recommendation on learn how to handle that should you see your startup quantity filling unexpectedly.)
Then, inside an hour of mounting a drive’s Time Machine quantity related to any Macs (and chosen volumes) which have had modified information, Time Machine on these computer systems will switch over the domestically cached snapshots and delete them, after which start common hourly backups once more so long as the drive stays mounted.
As famous in lots of earlier columns, you can even have a number of Time Machine locations plugged in without delay or chosen as locations, after which use that to rotate on-site and off-site drives for extra backup safety towards hearth, theft, or accident.
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