Time Machine Backup Size Keeps Growing and Failing

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Time Machine Backup Size Keeps Growing and Failing

I have been using a 3TB Time Capsule (802.11ac / Firmware version 7.7.9) for many years without any issues. I am using it as a router and as a backup drive for my Mid 2011 iMac 27" / 2.7GHz Core i5 / 16GB RAM running macOS High Sierra 10.13.6.

Recently, a message appeared on my computer:

“Time Machine completed a verification of your backups on Data (name of the backup drive). To improve reliability, Time Machine must create a new backup for you.”

Since then, Time Machine has been incapable of recreating a full backup of my computer. It starts backing up, gets close to the end and then the backup size keeps growing and growing and growing until there is no more space on the Time Capsule and Time Machine tells me that the backup failed.

I tried erasing and reformatting the Time Capsule Drive via Disk Utility, but the result is the same and the backups keep failing because their size keeps growing for no apparent reason. I have around 1.5TB of data on my computer and the Time Capsule has 3TB of space, so there shouldn't be a problem backing

Any help with this issue would be greatly appreciated!

Posted on Oct 26, 2018 9:38 PM

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Answer 1

Top-ranking reply

Bob Timmons

Community+ 2024

Level 10

168,668 points

Oct 28, 2018 11:39 PM in response to md_from_mtl

Better to do a Zero Out Data Erase to completely and securely erase the drive. It will take some time though.

On your Mac.....

Open Disk Utility

Select Macintosh HD, or whatever the name of the Mac's hard drive might be....and run First Aid at the top of the Disk Utility window

When the Zero Out Data erase has completed, power off and restart the Time Capsule

Restart your Mac

If possible, temporarily connect your Mac to the Time Capsule using a wired Ethernet cable connection and turn off the WiFi on the Mac

Try to run a backup again

You may likely see that Time Machine is "Preparing" for a long time.....sometimes 3-4 hours or more.....before the backup will actually begin. Let things run until the process is done, or until you see an error message.

If you see the same errors as before, then it is time to suspect a hardware defect on the Time Capsule hard drive.

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Answer 2

md_from_mtl Author

Level 1

14 points

Oct 27, 2018 11:23 AM in response to MrHoffman

It doesn't look like this is a hardware issue. Reading the support pages, Apple says the Time Capsule performs a hardware check when you restart it from the Airport Utility app - which I have done. The fact that the yellow blinking light turns to green after restarting the Time Capsule seems to indicate that the hardware is fine.

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Answer 3

Oct 27, 2018 12:40 PM in response to md_from_mtl

And the hardware is fine, for two-thirds of the backup. Then it's not fine. Diags don't always find these.

Try a different Time Machine target, and maybe try reloading the TC, try a different Mac trying to use the same TC, etc. Run some tests, see what works and what doesn't, and where the problems arise.

But a many-years-old TC is certainly also ripe for a failing hard disk drive or for a failing power supply, too.

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Answer 4

Oct 27, 2018 1:07 PM in response to md_from_mtl

I tried erasing and reformatting the Time Capsule Drive via Disk Utility

Normally, it would not be possible to erase the Time Capsule drive using Disk Utility.....unless you know some special tricks that may or may not work.

Usually, you would use AirPort Utility to erase the Time Capsule drive. Perhaps that is what you meant to say? If yes, which type of Erase......Quick, Zero Out, 7 Pass, etc......did you perform?

There is at least one more check to make on your Mac's hard drive, but let's get clarification on how you erased the Time Capsule drive first.

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Answer 5

md_from_mtl Author

Level 1

14 points

Oct 27, 2018 1:35 PM in response to md_from_mtl

There might be one thing I should add. There is a separate USB drive attached to the Time Capsule. I’m using this drive to do Time Machine backups of my other computer, a MacBook Pro running macOS Mojave 10.14.

There have been no issues so far with this setup.

But the Time Machine backups of my iMac (running macOS High Sierra 10.13.6), which are supposed to be stored on the Time Capsule’s internal hard drive, repeatedly fail, as described in my initial post.

Maybe it has nothing to do with the issue, but I thought I’d mention it just in case...

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Answer 6

md_from_mtl Author

Level 1

14 points

Oct 29, 2018 12:03 AM in response to Bob Timmons

Ok, so it seems like the problem has been solved!

Here's precisely what I did, mostly following Bob Timmons' advice :

1) I "zero out data" erased the Time Capsule' hard drive, using Airport Utility. The Time Capsule was absolutely full by then (1.5GB remaining on a 3TB drive) so that was a lengthy operation. It took over 6 hours to complete.

2) I ran First Aid via Disk Utility on my Macintosh HD. No issues were reported, so no repair was necessary.

3) I rebooted the Time Capsule (via Airport Utility).

4) I rebooted the iMac.

5) While rebooting the iMac, I flushed the PRAM. I don't know if that part is essential but it's an easy thing to do so why not.

6) I did not connect my iMac to the Time Capsule with an ethernet cable. Not that I didn't want to do so, but due to the layout of my house it wasn't really possible or practical to do that.

7) Once the iMac was running, I opened the Time Machine System Preferences, selected the Time Capsule hard drive as the destination for the Time Machine backup and launched the backup. Since the backup was done over wifi and weighed about 500GB, it was, again, a lengthy process. It took somewhere around 11-12 hours to complete.

But the good news is that this time the backup did complete! Gone is that strange phenomenon where the size of the backup keeps growing until the Time Capsule is completely full, and then fails!

So, thank you Bob Timmons for your advice. It is much appreciated and it helped a lot here.

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