Not sure. You might want to see if the --checksum option is enabled (or disabled?). Also, rsync man page says it does a checksum even without that option, to

Not sure. You might want to see if the --checksum option is enabled (or disabled?). Also, rsync man page says it does a checksum even without that option, to verify the file has been copied correctly. This may be what is causing a lot of I/O. I also forgot to mention that hashdeep/md5deep should probably be integrated into this sort of backup system (http://md5deep.sourceforge.net/ http://md5deep.sourceforge.net/). What hashdeep does is generates a list of checksums for a given backup. You would store this list with the backup, and then use hashdeep to "audit" the backup when you restore it, or to check if hardware is failing.