Time Machine issues

TidBITS Talk
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I ran into some issues with Time Machine last night. But first let me back up a bit and describe what triggered this.

I was testing some new software. One of the applications did what I consider a serious NO-NO and deleted my copy of a utility stored in /usr/local/bin and replaced it with its own…somewhere. Couldn’t find it but also didn’t try too hard. I emailed the developer and he suggested that I reinstall my version in /usr/local/bin. But it may have done other improper things, too, so…

…Having just completed an incremental backup using SuperDuper! a few hours earlier I thought it might be best to do a restore from the external backup drive to the internal startup drive.

This is where the problem arises. The next time that TimeMachine ran (I only run it once/day) it declared that I did not have enough space remaining on the TM drive to back up all the new/changed files on the internal drive. It appears that many files were changed (at least TM thinks so) during the restore and the total size was too big.

Anyway, I have decided to retire this TM drive and have ordered a new one. I already have a shelf of old, retired TM drives and this one will be in good company.

Any ideas why TM behaved in this manner?

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My initial guess is that all the deletes and writes preformed by SuperDuper! restoring your files are being tracked in the macOS FSEvents database. Time Machine reads that database to determine the files that have been changed and need to be copied to the backup storage. Every file you restored from your backup was probably logged.

Time Machine makes no effort to determine if the contents of the files are exactly the same as the copy you have on your backup medium.

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I think I found the issue but I’m not sure why it occurred.

The SuperDuper! restore worked as it should. I have examined the logs from the backup done Monday morning and the restore done on Monday evening. All seems correct.

Time Machine attempted to include another drive in its backup. I used BackupLoupe to check all of my previous TM activity and TM has never backed up this drive until yesterday. The drive had been “Excluded” in the TM preferences but that exclusion was missing yesterday. Perhaps the Backup/Restore caused this issue with the Exclusion list.

Anyway, I used TM to delete the files associated with the other drive and now I have my disk space back.

Time Machine is great…except for when it does weird stuff.

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