[josho]

What is the user experience for when a checksumming filesystem detects an error?

If the fs detects a bit error does it flag the file as entirely unreadable? Move it to lost+found? Force me to restore the file from a backup? All these options seem more scary for an end user than blissful ignorance.

Don't misunderstand me, I've lost a few family photos over the years due to bit rot. So, I appreciate a fs that offers more protections. But, I honestly don't know offhand how an end user would recover from an error in /System or even an error in a family photo, or for that matter a word doc.

[glhaynes]

If the fs detects a bit error does it flag the file as entirely unreadable? Move it to lost+found? Force me to restore the file from a backup?

For files stored in iCloud Drive, if that version of the file exists in the cloud, the OS could automatically re-fetch the file. But, yeah, for lots of circumstances there's not going to be a "good" option to give the user.

EDIT: Same applies to Time Machine (or whatever Apple's backup solution will be called in the APFS era).

[mindajar]

It was a stealthy feature addition that went totally unannounced, but as of 10.11, Time Machine stores file checksums in the backup. See 'tmutil verifyChecksums'.