power.wang,  Firstly, please consider moving this discussion to the appropriate community for maximum visibility.  You can do so by selecting "Move discussion" in the upper-right corner and selecting, in this case:  All Places > Support Community > CLARiiON Support Forum  To answer your question, it will be the first disk selected when creating the RAID Group.  Search for the following KB article:  emc117289: "How do you determine which physical disk is the parity disk in a RAID 3?"
as title! maybe by command or some way else...
can we figer out which disk is parity disk in RAID3?