Time Machine couldn't complete the backup

Question

Time Machine couldn't complete the backup

Time Machine couldn’t complete the backup to iMac Back-up Drives

This is the ERROR Message I Get: 'The backup disk needs 1.05 TB for the backup but only 401.54 GB are available. Select a larger backup disk or make the backup smaller by excluding files.'

My Time Machine back up drives (I have 2) are 8TB hard drives. My iMac has a 1TB SSD drive. I believe Time Machine should automatically delete the oldest backup to make room for new backups. But for some reason, it is not doing so.

Does anyone know what I should do to correct this situation so that new Time Machine backups can resume?

iMac 27″ 5K

Posted on Mar 8, 2023 7:05 PM

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Answer 1

Best reply

Ravihaninwal

Level 1

76 points

Mar 11, 2023 3:54 PM in response to Colorado Mac Daddy

Based on the error message, it seems like your Time Machine backup drives are running out of space to store new backups. Time Machine is designed to automatically delete the oldest backups to make room for new ones, but it's possible that something may be preventing it from doing so.

Here are some steps you can try to resolve the issue:

1. First, check to make sure that your Time Machine backup settings are configured correctly. Go to System Preferences > Time Machine and make sure that your backup drives are selected as the backup destination.

2. If your backup drives are selected as the backup destination, try removing some files from your iMac to reduce the amount of data that needs to be backed up. This can be done by manually deleting files or using the Time Machine interface to exclude certain folders from the backup.

3. If the above steps don't work, try resetting Time Machine by turning it off and then back on again. To do this, go to System Preferences > Time Machine and click the "Off" button. Then, turn Time Machine back on and try running the backup again.

4. If none of the above steps work, you may need to manually delete some of the old backups to free up space. To do this, connect one of your backup drives to your iMac and open it in Finder. Then, navigate to the folder that contains your Time Machine backups (it should be called "Backups.backupdb") and manually delete some of the oldest backups. Be careful not to delete any recent backups that you may need to restore from in the future.

Hopefully, one of these steps will help you resolve the issue and resume your Time Machine backups.

# If you're still encountering issues with Time Machine, you may want to consider verifying the health of your backup drives. It's possible that one of the drives is failing or has become corrupted, which could be preventing Time Machine from deleting old backups or storing new ones.

1. You can use Disk Utility to check the health of your backup drives. Connect one of your backup drives to your iMac and open Disk Utility. Then, select the drive from the left-hand sidebar and click on the "First Aid" button. This will run a diagnostic check on the drive and repair any issues it finds.

2. If Disk Utility is unable to repair the drive, it may be time to replace it with a new one.

# Finally, if none of these steps work, you can try restarting your iMac and/or your backup drives. This can sometimes resolve issues with Time Machine or other software that may be causing conflicts.

If you continue to encounter problems with Time Machine, you may want to consider contacting Apple support or consulting with a professional technician to help diagnose and resolve the issue.

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Answer 2

den.thed

Level 9

77,404 points

Mar 9, 2023 7:04 AM in response to Colorado Mac Daddy

Sounds like maybe your Time Machine drive(s) are backing up another external drive or perhaps even each other.

Go to Apple > System Preferences or Settings in Ventura > Click on Time Machine > click Options > click the Add + Plus > Add any external drives or the other Time Machine backup drive to the Exclude list.

see > Exclude files from a Time Machine backup on Mac - Apple Support

If that does not help or by default both are already Excluded, then I would consider erasing one of the Time Machine backup drives and starting over fresh.

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Answer 3

rkaufmann87

Level 10

140,868 points

Mar 8, 2023 7:10 PM in response to Colorado Mac Daddy

It may help us if you provided more than just a statement. Such as:

• Version of Mac OS installed on the Mac.

• What brand & model of External Hard Disk you are using for Time Machine.

• How much available space there is on the Time Machine drive.

• What troubleshooting you have attempted.

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Answer 4

Mar 10, 2023 3:37 AM in response to rkaufmann87

Yes, here is more specific information:

The Computer: 2017 iMac / MacOS Catalina 10.15.7 / 40GB DDR4 /

I have been using time machine to back up my current iMac since purchased in 2017. I am using two naked 8TB Western Digital 3.5" Drives with an OWC Dual Drive Dock to have a redundant backup of my iMac. One of the Drives (The "A Drive" back-up drive has 401.11 GB of 8TB remaining.

This "A Drive" back-up Drive is failing to back up and displays the following notification message:

"Time Machine couldn’t complete the backup to iMac Back-up Drive"

"The backup disk needs 1.05 TB for the backup but only 401.54 GB are available. Select a larger backup disk or make the backup smaller by excluding files. Last successful backup: Februrary 25, 2023"

The 2nd "B Drive" back-up drive has 519 GB of 8 TB remaining. It is backing up as normal. My iMac has internal 1 TB SSD storage.

Time Machine has been backing up to both back-up drives as normal with this set up since I set it up 3 years ago.

I performed Disk Utility's First Aid on th "A-Drive" back-up drive to see if there is a problem with the back-up disk or catalog. These are the results:

DISK UTILITY RESULTS:

"Repairing file system.

Volume was successfully unmounted.

Performing fsck_hfs -fy -x /dev/rdisk6s2

Checking Journaled HFS Plus volume.

Checking extents overflow file.

Checking catalog file.

Checking multi-linked files.

Checking catalog hierarchy.

Checking extended attributes file.

Checking multi-linked directories.

Checking volume bitmap.

Checking volume information.

File system check exit code is 0.

Restoring the original state found as mounted.

Operation successful."

In System Preferences, Time Machine states the following:

Time Machine keeps:

Local snapshops as space permits

Hourly backups for the past 24 hours

Daily backups for the past month

Weekly backups for all the previous months

The oldest backups are deleted when your disk becomes full.

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Answer 5

Mar 11, 2023 3:47 PM in response to den.thed

Thanks for your help and suggestions.

Both Back-up drives and all other external drives are on the Exclude List.

Indeed I may need to erase and one of the Time Machine backup drives and start anew. But I would still like to know why Time Machine is not functioning as intended by erasing the oldest backups to make room for new backups. It isn't a huge deal for me because I do have a 2nd backup drive. But if I did not, that would not be a very safe backup strategy. Thanks again!!!

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Answer 6

den.thed

Level 9

77,404 points

Mar 11, 2023 4:17 PM in response to Colorado Mac Daddy

You’re welcome.

This is a perfect example, of why I have never fully relied on a single external drive and/or Time Machine.

Fact is, I was using CarbonCopyCloner years before Apple came out with Time Machine. These days I make weekly and monthly CCC clone backups on external SSDs and then run Time Machine on an external HDD for the sake of it.

Besides it is like 10 times faster to recover or migrate to a new Mac using a lean CCC clone on an SSD, than it is to migrate from a bulging Time Machine backup on a slow HDD.

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Answer 7

Mar 11, 2023 4:40 PM in response to den.thed

That's not a bad idea! I have heard lots of good things about Carbon Copy Cloner over the years. Of course, what I like about Time Machine is the set it and forget it aspect. But, I do see the benefit of having a plan B backup strategy!

Thanks for the suggestion. I will look into it.

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