I've been backing up my Mac with Time Machine on an external hard drive for several years. I recently plugged the external drive into my Mac, it spent a long time running fsck_hfs and finally showed this dialog:

Running disk utility gives a lot of Invalid extent entry messages along with the conclusion First Aid process has failed.

My intuition would be to copy the whole disk to a new drive. I have a vague recollection from learning about Time Machine several years ago that this would have to be block-wise in order to preserve the Time Machine backup (using dd or carbon copy cloner, right?). But presumably a block-wise copy of the drive would copy the extent errors as well? So do I just have to give up and lose my entire Time Machine history at this point?

1 Answer 1


No. Copying it to a new partition would remove the filesystem error. Finder will preserve the hard-linked folder for TM, while CLI tools like cp won't. Just drag the Backups.backupdb folder to a new partition and wait for Finder to finish.

Source: https://support.apple.com/en-us/HT202380

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