>> ... >> On 06/21/2018 09:53 AM, Andreas Dilger wrote: >> > Keep your old snapshot around after you create the new one, and run >> > "stat(1)" > on the same file in both snapshots to see if there are any >> > other >> differences > besides the device number that may be causing tar to think >> the file changed. >> Yes, this is the key. You need to find out why 'tar' thinks the >> directory has changed, and 'stat' should tell you why. >> >> ...
The problem seems to be caused by the changing of the inode of the root of that filesystem. The inode for the test filesystem's root directory is 3, the inode for various snapshots are numbers like: 281474976666177 281474976671479 281474976673971 So I applied the patch at the following URL to tar 1.30 (applied partially by hand because it had one hunk that was rejected): https://pastebin.com/ZjpqYJk3 Now if I run this test version of tar, I get a reasonable incremental size. Unfortunately, the patch only implements the feature, but no documentation or tests. Pieter
