Daniel Carosone wrote: > Something similar would be useful, and much more readily achievable, > from ZFS from such an application, and many others. Rather than a way > to compare reliably between two files for identity, I'ld liek a way to > compare identity of a single file between two points in time. If my > application can tell quickly that the file content is unaltered since > last time I saw the file, I can avoid rehashing the content and use a > stored value. If I can achieve this result for a whole directory > tree, even better.
This would be great for any kind of archiving software. Aren't zfs checksums already ready to solve this? If a file changes, it's dnodes' checksum changes, the checksum of the directory it is in and so forth all the way up to the uberblock. There may be ways a checksum changes without a real change in the files content, but the other way round should hold. If the checksum didn't change, the file didn't change. So the only missing link is a way to determine zfs's checksum for a file/directory/dataset. Am I missing something here? Of course atime update should be turned off, otherwise the checksum will get changed by the archiving agent. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
