Backing up two trees with corresponding files hard linked

Matt McCutchen hashproduct at
Thu Jan 19 15:20:48 GMT 2006

Today I went to back up my computer to an external disk with rsnapshot.
I have two copies of the Linux kernel; a few files differ, but matching
files are hard-linked between the two trees to save space.  Since I
didn't give -H to rsync, it is making a separate file on the backup disk
from each hard link on the source.

I had the understanding that -H used an O(n^2) algorithm to match up
hard links and it would be prohibitively expensive to use this option on
a filesystem with about 100,000 files.  Is this true?  If so, is there
or will there be a way to get rsync to take advantage of special
situations like my two hard-linked trees?
Matt McCutchen, ``hashproduct''
hashproduct at --

More information about the rsync mailing list