Time Machine Backup issue

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Time Machine Backup issue

I have a 1 TB HD on my Macbook Pro with 301 GB free space. I have a brand new 8 TB external drive used for backups. It has 4.29 TB used for the initial backup. The initial backup claims to be successful, but when I tried to restore to the initial backup it fails stating there isn’t enough space on “Macintosh HD”.

If my system has 699 GB to back up of 1 TB, then my 8 TB backup should be sufficient. Why did it used 4.29 TB to backup 699 GB? also, attempting to create a 2nd backup fails for the same reason (not enough disk space).

I think something is flawed with Time Machine. Is there a know issue with this and resolution?

MacBook Pro 16″, macOS 10.15

Posted on Oct 21, 2021 7:56 AM

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Answer 1

Top-ranking reply

Old Toad

Level 10

210,585 points

Oct 22, 2021 2:39 PM in response to GlarryProductions

If all else fails and you wouldn't lose any files by erasing your Time Machine drive then erase it and format it as APFS Case Sensitive with GUID partition. Then start a new TM backup and see what the size is when it finishes.

Also if the new 8TB drive came with any software on it and you installed it uninstall it. It's not needed for the OS to manage the drive and will only prove to be a hindrance.

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Answer 2

mario49

Community Specialist

Oct 22, 2021 9:16 AM in response to GlarryProductions

Hello GlarryProductions,

After reviewing your post, it seems like the Mac is not able to create a backup because there is not enough disk space. Your first Time Machine backup includes everything on your Mac. After that, Time Machine finds and saves only new and changed items, so the backups become smaller. There are a couple things you can try that may be able to help. We would recommend you read these articles and use them to help troubleshoot the issue.

If the Time Machine backup disk for your Mac is full

Free up storage space on your Mac

Please don't hesitate to let us know if you need additional assistance.

Thank you for using Apple Support Communities. Have a nice day.

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Answer 3

Oct 22, 2021 10:47 AM in response to mario49

I appreciate a response, but please do the math again on my original question:

Why did it use 4.29 TB to backup 699 GB?

That makes no sense.

Backups should be compressed and take up less space, not more.

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Answer 4

Oct 22, 2021 2:53 PM in response to Old Toad

I'll give that a try. FYI: I had deleted all of the "installed" software on it for starters, but had it formatted at Mac OS Extended out of ignorance. I would not have thought about using the APFS Case Sensitive option, but after looking it up, I see that APFS is for the O/S version I'm using and newer. I'm hopeful this will resolve the issue. Thank you in advance.

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Answer 5

Oct 26, 2021 6:54 PM in response to GlarryProductions

Formatting the new 8 TB external drive using APFS Case Sensitive option worked. I now have several days worth of good backups. My O/S version is Catalina 10.15.7 which is an upgrade from the original O/S (Mojave, I think) that my MacBook PRO came installed with.

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Answer 6

Old Toad

Level 10

210,585 points

Oct 22, 2021 3:34 PM in response to GlarryProductions

Keep us posted on your success or …

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Time Machine Backup issue

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