Yet Another Cycling Forum
General Category => The Knowledge => Ctrl-Alt-Del => Topic started by: Jurek on 03 October, 2021, 01:16:07 pm
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This morning I updated Big Sur on my 2020 MacBookAir.
It took ages to complete, probably over an hour.
Just now I updated Big Sur on my 2015 iMac.
It did it in about 30 seconds.
Why so the difference?
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Is it possible that the first one downloaded the update file and the second one used that file, rather than download it? I cant remember if OSx does that automatically, but it can do.
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It's a long time ago but I used to find that downloading from the main apple server could be very slow when a new updated arrived. A little while after it would be ok. I also found that if an update was slow give up on the graphical interface and get the update with the command line tool which used a different server.
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Would it be that the MacBook used wifi whereas the iMac was attached by a piece of string?
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I'd also considered whether that might be the case.
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The update on my 2015 MBP was about 4.5Gb. It didn't take long - maybe 25 minutes.
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The OS on Big Sur is read-only and cryptographically signed. When you do an update it has to download and replace the whole thing. There are no “updates”.
However due to the magic of snapshots on APFS, it can do this on a separate copy and do an instant switcheroo when it’s finished.
So your first computer had to do the work while you waited. Your second computer had already done all the work and just needed to switch the OS volume for the new one.