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Time Machine: First backup much larger than MacBook Air disk

I'm doing my first Time Machine backup of my MacBook Air with 250GB disk. This first backup is still going strong with 412GB backed up.


Why? What is going on here?


Thanks.

MacBook Air 13", macOS 10.15

Posted on Dec 31, 2019 9:49 AM

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Posted on Dec 31, 2019 10:02 AM

That seems weird. I have also had that, and patience, plus using Terminal to try to understand what is happening helpd


The command


printf '\e[3J' && log show --predicate 'subsystem == "com.apple.TimeMachine"' --info --last 24h | grep -F 'eMac' | grep -Fv 'etat' | awk -F']' '{print substr($0,1,19), $NF}'


issued in Terminal shows you the past 24 hours.


What I found with mine is that any interruption gave it indigestion, but that it finished, eventually, after I let it back up a stupendous amount, double my used internal storage plus an external drive with my Photos library

3 replies
Question marked as Top-ranking reply

Dec 31, 2019 10:02 AM in response to jtjbt20x

That seems weird. I have also had that, and patience, plus using Terminal to try to understand what is happening helpd


The command


printf '\e[3J' && log show --predicate 'subsystem == "com.apple.TimeMachine"' --info --last 24h | grep -F 'eMac' | grep -Fv 'etat' | awk -F']' '{print substr($0,1,19), $NF}'


issued in Terminal shows you the past 24 hours.


What I found with mine is that any interruption gave it indigestion, but that it finished, eventually, after I let it back up a stupendous amount, double my used internal storage plus an external drive with my Photos library

Dec 31, 2019 10:18 AM in response to Lurkums

The latest log entry:

2019-12-31 13:01:31  Copied 412.3 GB of 167.11 GB, 1,953,326 of 3,881,946 items (~0.03 MB/s, 1.14 items/s).


Also from the log I can see where the extra backup is coming from. My Dropbox app is set for all files to remain in the cloud (since I only have a 250GB disk) and the TM backup is pulling all the dropbox files down to the MacBook Air and then including them in the TM backup session.


Thanks for the info, it helped.

Dec 31, 2019 10:17 AM in response to jtjbt20x

Catalina seems to copy X of Y where X is greater than Y. I have no idea why it can't do arithmetic! The speed suggests it is handling myriads of tiny files. The number of items remaining looks interesting


If you go to System Preferences>Time Machine> Options you will see what is excluded from the backup. I have no experience of iCloud as a storage medium, but suspect it does not form part of a TM backup since iCloud is (probably) intended to handle that


I stick with the advice of "wait" adding to it "Ensure your machine does not sleep and that the backup can run to EOJ uninterrupted" which is hard if you need to take your laptop for a walk

Time Machine: First backup much larger than MacBook Air disk

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