ctime and mtime questions

[Richard Taubo <ort@bergersen.no>]

Hi!

Just wonder about a few things with tarsnap that I hope someone could answer:

1) When tarsnap is deciding if a file has been changed, does it compare 
checksums of all the files or are changes triggered by *ctime* changes since last backup?
If both can be used, what is the default?
(I see the "--newer date" entry in the man pages, and an example where subsequent
backups are performed, but the method of how it works does not seem to be mentioned). 

2) When restoring files from tarsnap, are *mtime* kept by default from when the files 
were backed up, and *ctime* and  *atime* set based on the time of the restore?
I am guessing the kernel will not allow for restoring the original *ctime*? 


Thanks!

Best regards,
Richard Taubo