ok so just a quick update I just removed the whole volume all together and recreated a new one using the 5 drives and its working . I don't know why it didn't want to expand the disk array , it may have not liked all the different size hard drives. I was using 2 x 4tb 2x 1tb and 1x 1.5tb in the cdrom bay which was the one I was trying to get to expand. What also happened which was a bit strange was that I removed one of the 1tb drives which made up 4 disk shr raid (which then change the shr to degraded status), and then replaced it with the spare 1.5tb from the cdrom bay which invoked the repair of the shr raid which fixed the shr raid again. But when I reinserted the original 1tb which was out of drive bay 4 and placed it into the cdrom bay to try and expand it again it totally crashed the shr raid hence the reason why i"m rebuilding the volume from scratch.