Hi there, On Sat, 28 Jul 2018, Guillermo Rozas wrote:
... rsync --checksum only checksums files on the client, not the server. I find this strange because not only the manual says otherwise ...
It is not clear to me what document ("manual") you are reading which leads you to the conclusions which you seem to have drawn. If you can give links to the document(s), and quote(s), that might assist. Quoting from the file .../backuppc-master/doc-src/BackupPC.pod which I downloaded today from Github: [quote] * Uses full-file MD5 digests, which are stored in the directory attrib files. Each backup directory only contains an empty attrib file whose name includes its own MD5 digest, which is used to look up the attrib file's contents in the pool. In turn, that file contains the metadata for every file in that directory, including each files's MD5 digest. [/quote] I take this to mean that, in order to find the checksums for the files on the client, the server looks in the files in its data directory for that client precisely because, when it does so, it does NOT then need to read pool files (to re-calculate the checksums) because it has done that work already and saved the results in the filesystem. Naturally, using this approach, you rely on the integrity of the previously saved pool data. That seems to me to be a very reasonable approach if, for example, (1) you are confident of the reliability of your power supply, your hardware, and your choices of OS and filesystem; (2) the backup server is dedicated to the task (perhaps even if it is a shared server but the backup data store is on a dedicated partition) so you can be confident that errant processes will not unexpectedly damage the data; and (3) neither life nor limb will depend on the backup. Also from the same document: [quote] * An rsync "full" backup now uses --checksum (instead of --ignore-times), which is much more efficient on the server side - the server just needs to check the full-file checksum computed by the client, together with the mtime, nlinks, size attributes, to see if the file has changed. If you want a more conservative approach, you can change it back to --ignore-times, which requires the server to send block checksums to the client. [/quote] This seems to me further to confirm my interpretation of the earlier quote, and also to suggest the behaviour which you yourself describe in your posts. It explicitly refers to "a more conservative approach" which may be what you want. -- 73, Ged. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/