Hyper-v Pass-through Disk format error

2 node cluster hyper-v WIN2K8R2.  Have a guest VM WIN2K8R2 that I am trying to attached pass through disk to.  Attaching to scsi interface within the vm.  I already have an existing 2TB passthru working no issues.  The new disk im adding is 4.5TB.  It seems to attach ok, but cannot format the disk, just get message "Format did not complete successfully".  This is all from Dell shared storage SAN.  Windows disk types are Basic mode.  Does a pass-through disk need to be converted to a windows dynamic disk type (not referring to fixed vs dynamic vhd's since not using a vhd)?