xfsdump and level tracking

[Greg Freemyer <freemyer@xxxxxxxxxxxxxxxxx>]

I'm curious how xfsdump does level tracking for backups.

In general it seems to work really well, but I have seen one case where I 
thought the same file was being backed up over and over again.

That was some time ago, but now I'm wondering if a screwed timestamp could 
cause this.

i.e. If I touch a file 60 days in the future, will every backup for 60 days 
include that file?

If not, how does xfsdump keep track of the fact that the file has been backed 
up?

Thanks
Greg
-- 
Greg Freemyer