https://bugzilla.samba.org/show_bug.cgi?id=13735
Wayne Davison <wa...@opencoder.net> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |WONTFIX --- Comment #2 from Wayne Davison <wa...@opencoder.net> --- Yes, the quick-check algorithm relies on the user and the apps to not make a data change and then back-date the mtime to lie about when the file was last modified. To help deal with this hiding of changes, the rsync patches repo has several checksum-caching idioms that accelerate a --checksum transfer. My favorite is db.diff that allows you to stash off checksum info in a local SQLite db file (or even a shared Mysql db). Such a setup doesn't avoid all redundant checksum computations (since the ctime can change on a file that has no data changes), but it does make checksum transfers MUCH faster. As Kevin mentions, the --checksum algorithm could also be improved to make it more selective, but that would require a protocol change and (in the simplest generator modification) we'd need to make the generator sit around and wait for its requested checksum data for each file that needs it before finishing up the current file and moving on to check the next one. Such a revised checksum method would be required for any maybe-checksum processing, such as the options you propose. Your options would also require adding in ctime info into the file lists. One nice thing about the checksum-caching patches is that you can make use of the optimization on just one side of the transfer and the other side gets the normal checksum-using file data. It also allows the sharing of updated checksum info between multiple rsync copies (whereas your suggested options would require each source/destination ctime difference to re-compute the checksum). -- You are receiving this mail because: You are the QA Contact for the bug. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html