Not (unfortunately) speaking from my own experience, just from Googling: https://serverfault.com/questions/211005/rsync-difference-between-checksum-and-ignore-times-options
discusses a —ignore-times option that may be useful. The upside is that it uses the minimum amount of network bandwidth but at the cost of checksumming everything on both sides. May take a while if you have a big stash of video files. However, there’s a —checksum-choice option that, with some testing of choices, might give you a quick-and-dirty checksum that’s good enough for your purposes. Your backup files , hopefully, are not corrupted. I was just wondering why your new backup seemed to want to transfer everything all over again. Just speculating, but maybe timestamps got changed in the NAS box work you did? I saw a post (that I can’t find now) that discussed the —modify-window option. This, I gather, is used when rsyncing between 2 different filesystems with different ideas about how precise to make the timestamps. A high precision timestamp file system’s timestamp will be a little different from a low precision timestamp file system’s timestamp, and will appear to be different timestamps to rsync, even though ls -l reports the same times. The stat command will give you full precision times, and maybe that will show a discrepancy. The —modify-window option lets you fudge subtle time differences. This is just speculation, and maybe an exotic and unlikely one, and definitely something I’ve never done myself. Another idea (again something I Googled but have never done) is to use the mtree utility. Apparently you can use this to write out the characteristics of a directory hierarchy - things like owner, permissions, checksum, size, timestamps, etc. on every file under that directory. Save this output to a file, then run mtree with this file as input on another directory hierarchy, say the backup on your NAS. Looks like you can use it to just check for differences, or you can use it to correct differences. If your timestamps were different on your video machine and your backup NAS, this looks like a way to make them match without transferring files. Hope a little of this was useful. Good luck! John Blinka
