Should I upgrade my Time Machine drive for successful backups?

Time Machine works best when your backup drive is 3 times the size of the data you are backing up. So in your case, ideally, you would need a 21 TB drive. You could probably get away with a 15 TB drive. But any smaller than that and you will regularly get errors like this.

Normally that's not too big of a deal. You can just wipe the Time Machine drive and start over. But that's a lot of data. Do you really need hourly-ish backups of 7 TB of data? I recommend using Time Machine only for your boot volume. Keep separate archives of external drives. You shouldn't be able to regularly churn 7 TB of data. But if you do, then Time Machine might be appropriate. You'll just need a bigger drive or rebuild when it flakes out.

dcnc wrote:

2015 iMac running 12.7.4, can't upgrade because of older machine.

I have three external drives each new 4 TB SSD's. They have .4 TB, 3.4 TB and 3.5TB of data. So around 7.3 TB of data. My Time Machine drive is 10 TB and Get Info says it has 2.8 TB of available space.

I've never had a backup problem but just got this message "Time Machine could not back up the disk “Videos” because a snapshot of the disk could not be created." I read that this could be about space. Do I need a bigger drive even though it has been working with no issues until now and has 2.8TB of available space? Other than a few office docs I've not added any new data.

How to delete Time Machine snapshots on your Mac.  

Often caused if the Time Machine Drive has not been attached  to the computer and TM Backup is set to run on a Schedule. 

TM Backup will make Snap Shot on the Internal Drive awaiting the TM Backup Drive to be attached. 

Only then will the Snaps Shots be transferred to the External Drive and deleted the Snapshot from Internal Drive.

There has been a recent infestation of these Forums by AI / ChatBots.

They may appear as well formulated  with what appears as possible technical solutions.

Suggest being very careful about this.

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