Hard links and sparse files

[andrewchambers]

Bupstash supports these, I don't know about the other tools.

[deajan]

I need to understand before adding this to the comparaison table:

• hardlinks
  • does bupstash have an option to explicitly avoid or follow them ? (Did a quick search on bupstash.io, didn't find any doc)
• sparse files
  • does bupstash know which files are sparse files, so it will not actually try to compress / dedup the empty part of the file ?

[andrewchambers]

I think you are confusing hardlinks and symlinks. On linux you create a hardlink with ln and a symlink with ln -s. A hard link looks as if they are a normal file but actually both point to the same inode on the filesystem.

I mainly mean if you backup a filesystem that has hardlinks and sparse files does the backup tool preserve and restore them or discard that information. It can be quite important this information is not lost. As an example if sparse file information is not restored properly you can run out of disk space when trying to restore files that previously fit on a disk.

[deajan]

Indeed, read too fast for the hardlinks. I've updated the comparaison with your requests. Thanks.