I have a file server that we are doing rsync's of the data to two different servers for backup purposes. Only problem, is that it seems like every time it's trying to copy the same files over and over, overwriting the files that it should be skipping. I'm assuming this is because one rsync modifies a time stamp or something on the file, so the next rsync thinks it has been updated so copies it again.

Do you guys think that is the problem? I see options like --modify-window and stuff, but what do you think is best? I'm rsync'ing between ext3/4 volumes always.

Looks like --size-only solved the issue the easiest in my testing, but do you think I had the scenario correct for the cause of the issue?