3 ms·
It's former. It splits files into blocks (defaulting to 32KB, but that's configurable), computes hashes (two separate hashes per block) and stores them in a fil
by latitude 12y ago
It's former. It splits files into blocks (defaulting to 32KB, but that's configurable), computes hashes (two separate hashes per block) and stores them in a file in the backup config directory. These are used to detect modified blocks. It also computes a hash of an entire file and stores it in the same hash file. This is used to hedge against false negatives with modified block detection. The original version (from '09) didn't use the full-file hash, so it resorted to re-copying files in full after several incremental updates.
- kijin 12y agoIs the full-file hash actually faster than re-copying the whole file? Re-calculating a full-file hash will require reading the whole file anyway. Which will take around the same amount of time as re-copying the whole file, since the sequential write speeds of most HDDs and non-entry-level SSDs are similar to their sequential read speeds. The only benefit would seem to be that your SSD might last a bit longer... but how many consumers use SSDs to store their backups? Please let me know if I'm missing something.
- latitude 12y agoYes, it is faster.
- rakoo 12y agoDo you use the rsync algorithm, so that bytes additions/deletions are efficiently handled ?