ceph-deploy osd prepare is ensuring there is a filesystem on the disk according to the args passed to ceph.conf (above). 

timeout: It has a long timeout because of the format taking forever. A resonable amount of time would be around 300 times the length of $osd_nodes. Right now its 0 to prevent puppet from aborting it.

tries: there is a race condition that this is preventing, after the 'ceph-deploy create mon' the bootstrap and admin keys must exist before the osd commands can be issued. This however requires the mon node to establish a quorum prior which takes 10-15 seconds for me. because 'ceph-deploy create mon' or 'ceph-deploy gather-keys' doesn't block, this seemed like an OK place to block, but it really should be in with 'ceph-deploy gather-keys'