Hello everyone, I installed macOS on a used iMac I bought and configured Time Machine. However, Time Machine backups failed to complete. Therefore, I used Disk Utility's "First Aid" to check if the external drive is ok and received error messages. I thought the drive was damaged. However, I partitioned the drive again and then everything worked and "First Aid" said the drive was ok. That got me thinking. A few weeks ago, I threw my old external hard drive in a box of electrics trash because I thought it was broken because Time Machine backups failed to complete and "First Aid" threw errors. Therefore, I picked it up from the trash pile, connected it and now suddenly everything works and the drive seems to be ok after all. 1) Have you experienced something similar? 2) How can I determine with confidence if a drive is ok or damaged if Disk Utility's "First Aid" seems unreliable?