Can I rsync my library?

[haertig]

Originally Posted by Cactus Chef

Otherwise, I probably need to do one more rsync and turn off --ignore-existing just to make sure I'm truly getting everything. If I'm remembering my rsync-fu, even if it flags my entire library as needing to copy, it should basically skip the files and transfer 0/0 bytes on each one when it determines that the hashes between the source and destination of each EPUB are the same, right?

I don't know about rsync ports to other OS'es, but from the Linux perspective, by default rsync selects which files to copy based on a changed timestamp or a changed file size. Related to this, I can envision potential issues determining what needs to be copied or not if you are rsync'ing from one OS to a different OS that doesn't manage timestamps in the same manner. Or if using CIFS or Samba or something like that. Rsync does not automatically use a hash of file contents to determine if a copy is required or not - you have to tell it that is what you want it to do with the --checksum option.

You definitely want to turn off --ignore-existing. Permanently. That kills the majority of the purpose for the backup in this case where things are changing (e.g., metadata.db)

[JSWolf]

Originally Posted by haertig

You definitely want to turn off --ignore-existing. Permanently. That kills the majority of the purpose for the backup in this case where things are changing (e.g., metadata.db)

yes you do want to turn off --ignore-existing. You want to let rsync add or remove content as needed. based on the fast that the file have a different date and/or file size.

[haertig]

--ignore-existing will cause rsync to NOT copy a modified file over an earlier version of itself that is already on the backup side. This behavior would be a disaster when copying Calibre via rsync, as the metadata files can change frequently. You would want the newest one, not the oldest.

It is rare that you want this "prefer older version over newer version" behavior. The usual reason is when you want to keep a historical chain of all versions of the file. This is typical for sophisticated backup systems that use advanced rsync capabilities like linking. But it is not that common for simple rsync invocations for non-experts.

[Quoth]

Originally Posted by haertig

--ignore-existing will cause rsync to NOT copy a modified file over an earlier version of itself that is already on the backup side. This behavior would be a disaster when copying Calibre via rsync, as the metadata files can change frequently. You would want the newest one, not the oldest.

It is rare that you want this "prefer older version over newer version" behavior.

I've never seen the option being used. Basically you only get entirely new files sent and no updates at all.