It's more less common knowledge that Time Machine uses hard links to represent files in the backup set that have not been modified during this time period, so they are linked to the most recent actual data in a previous backup set to save space.
It's also true that the Mac GUI gives a user absolutely no capability to create hard links in any context at all. They have to be created in terminal using the UNIX underpinnings directly. So it's not a big leap of faith to assume that the design of time machine supports backup only of "Mac standard" file layouts, and that when time machine sees a hard link in its data, it assumes that it and only it could've created it... so it treats it in its own standard fashion when restoring it. Bottom line is, you could submit this to bug reporter as an enhancement, but I don't think it will be accepted. > On Aug 13, 2017, at 12:02 PM, Michael <keybou...@gmail.com> wrote: > > ACK! > > So I just found out that time machine does not backup hard links. Nor does it > backup meta-data to permit restoring hard links. > > Repeat by: > > keybounceMBP:~ michael$ mkdir test-link > keybounceMBP:~ michael$ cd test-link > keybounceMBP:test-link michael$ echo file a > a > keybounceMBP:test-link michael$ ln a b > keybounceMBP:test-link michael$ ln b c > keybounceMBP:test-link michael$ ln c d > keybounceMBP:test-link michael$ ln d e > keybounceMBP:test-link michael$ ls -li > total 20 > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 a > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 b > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 c > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 d > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 e > keybounceMBP:test-link michael$ tmutil startbackup -b > Total copied: 760.28 MB (797214702 bytes) > Avg speed: 1231.99 MB/min (21530541 bytes/sec) > > After restoring from time machine: > > keybounceMBP:~ michael$ ls -li test-link* > test-link: > total 20 > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 a > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 b > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 c > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 d > 35248494 4 -rw-r--r-- 5 michael admin 7 Aug 13 11:27 e > > 'test-link (original)': > total 20 > 35248827 4 -rw-r--r-- 1 michael admin 7 Aug 13 11:27 a > 35248828 4 -rw-r--r-- 1 michael admin 7 Aug 13 11:27 b > 35248829 4 -rw-r--r-- 1 michael admin 7 Aug 13 11:27 c > 35248830 4 -rw-r--r-- 1 michael admin 7 Aug 13 11:27 d > 35248831 4 -rw-r--r-- 1 michael admin 7 Aug 13 11:27 e > keybounceMBP:~ michael$ > > Note that the restores are all different files. > > This is on 10.9.5. Does this still happen (no hard-links after restoring) on > 10.12? > > What is the best way to backup a file system? The goal is "perfect > restoration" (including meta data / file structure, not just data > restoration), with historical replication (so not just disk cloning)? > > --- > Entertaining minecraft videos > http://YouTube.com/keybounce > > _______________________________________________ > MacOSX-talk mailing list > MacOSX-talk@omnigroup.com > http://www.omnigroup.com/mailman/listinfo/macosx-talk _______________________________________________ MacOSX-talk mailing list MacOSX-talk@omnigroup.com http://www.omnigroup.com/mailman/listinfo/macosx-talk
