When I upgraded my iMac to Monterey I noticed that Time machine had stopped working. The OS had reformatted the Time Capsule hard drive to APFS but wasn’t completing the backup. After several attempts where it did not recognize the previous backup and added another 400 GB to my backup drive each time, I decided to revisit my backup strategy and updated to Joe Kissell’s lates version of backing up your mac for guidance.
I selected a 2 TB Thunderbolt 3 SSD (same size as the fusion drive on my iMac.) I formatted it as APFS encrypted and then offered it to Time machine as a backup location. Again time machine failed.
I tried using Clean My Mac to remove potentially troublesome files, but it did’t catch everything. I then used System Information to identify 32 bit apps still on the machine and manually deleted each one using the identified path to locate them. (They were all inactive, circle slash)
I was able to do a complete backup in Safe Boot mode so I went back and removed all startup items. No luck.
I decided to exclude the users folder from Time machine backup - success.
I excluded all individual user folders - success
I only excluded my user folder - success
I excluded all folders in my user folder - success.
One by one I included each folder until only my user library folder was stopping the backup.
I then followed the same process in the Library and had three folders that were preventing backup success:
~/Library/Application Support 20.55 GB
~/Library/Group Containers 15.38 GB
~/Library/Mail 10.5 GB
I realize Mail could probably be resolved by deleting attachments, but at this point I was ready to claim success. I had a full backup from Safe Boot and wasn’t too concerned about backing up the other two ( I may regret this later).
So at this point Time Machine appeared to be working.
About a month later it stopped working again and showed no backups and reduced disk space available on my backup drive. I tried running disk first aid and discover it doesn’t work for APFS format. I could mount and unmount the backup disk and see the backup folders inside. Time Machine could not. I booted into recovery mode and was able to use disk utility first aid with my Time machine encryption password. No problems found on the backup disk. I did a normal restart and reselected the backup drive in Time machine. I still had the library files excluded. It did not recognize the existing backup and identified over 100K files that needed to be copied. I left it running and when I came back it was recognizing the previous backups and had a minimal increase in backup size.
- Backup works in Safe Boot mode (for me)
- The folder exclusion process seems to work. I have multiple files over 6 GB in size that it does not seem to have problems with. Just those three in my user library (for now)
- I believe when my computer crashes it throws off time machine and it can’t recover without help.
- I doubt reselecting the backup disk would have allowed it to recover if I didn’t have sufficient spaces on the disk for a second full backup.
BTW, I am seriously considering dumping Time machine in favor of Carbon Copy Cloner for this hourly backup function.