Over 200 GB had disappeared from my Mac ’s startup volume . It seemed improbable the external SSD I had just swapped in as my startup private road was shrivel up . Instead , it was a snapshot — more accurately , a snap for reverting the state of files on my volume or the integral intensity to a previous gunpoint in metre .

shot are a sinewy manner for backup software program to ply a quick point in sentence to walk back to when you do n’t necessarily take to restore the entire intensity . You might want an earliest interlingual rendition of a file , or the volume might be changed only slenderly , pretend it far faster to utilise a snapshot to revert it to a late province . That might pass if you accidentally overwrite a bunch of Indian file or ( heaven forbid ) you were snipe by ransomware . ( Ransomware is a likely risk for Mac exploiter , because of the simple-minded nature of how it work , but there have been no meaningful ransomware malware “ successes ” against macOS yet . )

You might encounter shot apparently filling your startup volume from one of two pieces of software :

Carbon Copy Cloner

Carbon Copy Cloner and snapshots

APFS allows the creation of a snapshotas a sort of “ fast rewind . ” Instead of restoring everything on your bulk , if you repair from an APFS shot , only the changes between the current State Department of your volume and the DoS of the snapshot motive be apply . The volume rewinds in meter to that point .

you’re able to also use the characteristic to recover older interpretation of a single file from the snapshot . Storing snapshots of files is calledversioning , and it ’s uncommitted through Time Machine if that backup method is enable ; through apps that keep going theFile > Revert To > surf All Versionsfeature , describe in this chromatography column , which make a new version for each save and for some auto - save performance ; and via sync software like Dropbox , which require a trip to the website to pull up previous versions .

snapshot let Carbon Copy Cloner recover older versions of files as well as intact volumes .

Carbon Copy Cloner

IDG

Bombich Software advocate snapshots as part of a bent of backup method that can help you get back in action more cursorily , and activate the feature of speech by default and only for SSDs . I had just switch from an internal Fusion drive ( a tiny SSD plus a large severe platter drive ) to an outside SSD , which is why I encountered the problem of a sudden .

But if you ’re using Time Machine and Dropbox or some other combination of software that keeps rescript on handwriting , you do n’t involve these snapshot or can set it to a depressed act .

InCarbon Copy Cloner > Preferences , uncheck “ Enable shot on APFS - initialize , SSD - backed volumes . ” After disenable , however , you could select a book in the sidebar under Volumes and see a list of snapshots and place setting to enable or disable snap .

Carbon Copy Cloner lets you pluck snapshot mise en scene to stave off retain too many .

If you ’re finding the snapshots are filling your mass too full , as I was , set the free space remaining preferences ( the bottom of the five context ) to a higher telephone number , like 150 GB or 200 GB . you’re able to also reduce the number of snapshots made and how long they ’re retained .

This Mac 911 clause is in response to a question submitted by Macworld reader Nick .

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