How can I backup my system to a remote server (AFP, Samba, or NFS share)?
Setup a new volume on your Nexenta/OS box for your backup and set it to share out as an iSCSI LUN. Then use one of several iSCSI initiators for MacOS X to attach the backup volume on your back. On your mac, format the volume as HFS+. Now you can use CCC or rsync, etc. to do your backups.