Problems with Change Detection

[buhtz]

This is a meta issue to coordinate and collect existing knowledge. Please prefer not to post here but in the related issues. Or open a fresh issue.

• "New" permissions handling in 1.2.0 causes re-backup of files that haven't changed #988
  • In here very important comment and detailed analysis
• Files with permissions r--r--r-- being repeatedly backed up #994
• Unchanged files are marked as changed #1028
• Make v1.1.x style permission handling configurable via expert settings. #1086
• Moved to Ubuntu Mate 20.04, backintime does full backup, few files have changed. #1093
• Remove new permissions handling #1128
• No backup if only file permissions modified but not the file content (was: changes in permissions not detected) #177
• Identical files copied even if checksum is checked #1073
• Files not being deleted from backup when deleted from source #993
• backup operation modifies previous backup dir's permissions #912
• restore doesn't preserve directory mtimes with "backup on restore" option #1007
• Support backing up file and folder attributes such as date and time created, ~~modified~~ and accessed. #2383
• atime is not preserved on restore #380
• Several files are backed up with each snapshot #1437

I start to form a slightly understanding... 🤣 🥳

• https://www.halfgaar.net/backing-up-unix (deep infos about change detection)
• https://rachelbythebay.com/w/2025/05/31/sync/