nas4free 22.214.171.124 under ESXi cannot handle physical RDM (raw device mapped) hard drives, but 126.96.36.199 can.
Trying to use such drive causes error as like "(da1:mpt0:0:1:0): unsupportable block size 0"
I'm guessing your actually meaning virtual RDM where you create a linking file object to a local hard drive vs a fiber channel connected disk which would be physical RDM.
I saw the same issue under the Paravirtual controller. It does work for me under the SAS controller.
I'm guessing this bug definitely caused by FreeBSD SCSI/CAM subsystem behavior, it handles RDMs pretty good in earlier nas4free builds.
First I thought there is a problem with the RDM in ESXi using a 3TB drive.
But now I can confirm this bug with NAS4Free 188.8.131.52.636. and 184.108.40.206.306.
I was giving 220.127.116.11.724 a spin and ran into this same bug. I'm using 2TB drives with RDM in ESXi 4.1.