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Initial Time Machine backup drastically slower than backing up manually

I set up Time Machine yesterday and it is taking MUCH longer to complete the initial backup compared to copying/backing up manually.


When I manually copied 2.5TB from one external drive to the other, it took 10 hours.


The initial Time Machine backup, of the same size, from the same disk to the other, is going to take 100+ hours.


I don't understand why this is so unreasonably long.

I cannot leave my MacBook at home for 100+ straight hours.

Posted on Jan 24, 2021 12:44 PM

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Posted on Jan 24, 2021 3:03 PM

Ok now the expected time is 16 hours, after couple minutes changes to 17, after a couple more minutes changed to 18 hrs. Now it is at 21 hrs 5 minutes after giving me the initial 16 hr estimation.


Great, if it keeps increasing like this I'll be back a 100+ hours again.


I shouldn't have to go through all of this trouble just to make Time Machine work reasonably. It should "just work".


Again like I said it took 10 hours to copy 2.5TB manually between the same drives

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Jan 24, 2021 3:03 PM in response to Frazzles_McNazzles

Ok now the expected time is 16 hours, after couple minutes changes to 17, after a couple more minutes changed to 18 hrs. Now it is at 21 hrs 5 minutes after giving me the initial 16 hr estimation.


Great, if it keeps increasing like this I'll be back a 100+ hours again.


I shouldn't have to go through all of this trouble just to make Time Machine work reasonably. It should "just work".


Again like I said it took 10 hours to copy 2.5TB manually between the same drives

Jan 24, 2021 2:55 PM in response to Frazzles_McNazzles

I'm trying:

  1. This terminal code "sudo sysctl debug.lowpri\_throttle_enabled=0" which I found here: https://all-about-apple.com/speed-time-machine-backups-terminal-trick/
  2. Open Spotlight and go to 'Privacy' & Add every drive you have! Steps 3 & 4 found here: https://forums.macrumors.com/threads/time-machine-slow-initial-backup-fix.379066/page-3?post=11016128#post-11016128
  3. "before you turn on TM backup anything you have on your intended time machine external disk, partition ( as GUID) first, then erase (format as HFS extended, journaled) and check/repair permissions. (dont let time machine format the disk)" found here: https://forums.macrumors.com/threads/time-machine-slow-initial-backup-fix.379066/?post=4422367#post-4422367
  4. Delete /Library/Preferences/com.apple.TimeMachine.plist and then restart

Will report back if works


Jan 24, 2021 3:05 PM in response to Frazzles_McNazzles

Time machine is intended to do its work in the background, without interrupting your important work.


So it usually computes what needs to be done and copies those files at low priority.


Time Machine's "claim to fame" is that it is the backup that gets done, because it does not ruin performance of the rest of the computer while doing its backup operations. You do not have to set aside a "Special Time" when you only do backups. When you need it, your Time machine Backup is much more likely to be there.


If you need to have it complete quickly, or you feel the need to watch it work, you have chosen the wrong tool.


Jan 24, 2021 3:11 PM in response to Grant Bennet-Alder

It doesn't matter what its claim to fame is if the initial backup takes so long that you cannot complete it.


It is unreasonable to think you can leave your MacBook plugged into large external drives for more than a weekend. You'll have to take it to work.


There is no excuse for not having an option within the program for it to work at full potential speed at least initially. There are many threads about this same issue.


I will never understand some people excessively defending apple. If you want to be sure something "just works" you correct these issues by again making said option available in the software. Pretty logical.

Jan 24, 2021 3:47 PM in response to Frazzles_McNazzles

It stabilized at 22 hrs; again compared to 10 hrs manually is ridiculous.

and going through all the trouble to get it from 100 hrs to 22 hrs is even more ridiculous.

Should logically have an option for full speed potential initial backups, with possibly a resource hog warning.


Grant I hope your future responses to others aren't more of the "your holding it wrong" variety.

Initial Time Machine backup drastically slower than backing up manually

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