I'm using rsync (over SSH) to back up files from my Macbook (v 10.6.7) to an external hard drive mounted on a server (not on my local network) running Ubuntu LTS 8.04.2. The partition on the hard drive is formatted HFS+. Rsync on both Macbook and server is 3.0.7.

I keep getting "Invalid Index Key" errors after a couple weeks of syncing. And eventually the syncs stop working altogether. If I reformat the partition on the external HDD, the syncs will start working again for awhile, but eventually I get the same error again.

I'd really like to get this working, so I can have reliable automated off-site backups. Any ideas?