Extracting changed files list from snapshot

[Bernard Dugas]

Lowell Gilbert wrote:
> Bernard Dugas <bernard at dugas-family.org> writes:
> 
>>I want to extract the list of files changed between 2 snapshots, to be
>>able to do efficient backups.
>>
>>Any idea where to find a document about snapshots internal structure ?
>>
>>Or if you know any port that already do this :-?
> 
> An easier way would be to generate an mtree(1) description for each
> snapshot, and using that to compare against other snapshots.  You have
> to mount the snapshot for that, though...

Thanks for your answer, sorry not to be clear on the goal : find the 
changed files without having to read the whole LARGE disk.

By definition, snapshot files have internally the list of block changed. 
So i would like to have a description of the internal structure of a 
snapshot file and a way to find the file by which any changed block is 
owned.

Best regards,
-- 
Bernard DUGAS Mobile +33 615 333 770