Metasan in my opinion is just capable of handling large SANs … Just not.. We have 2 dedicated metadata controllers and the system still falls down… Metadata controllers become unresponsive and then the volumes become corrupt.. It take 5-7 minutes to remove the volumes from the SAN definition each.. So 20 voolumes = 100 minutes plus JUST to remove the volume so that you can repair them….
My experience with MetaSAN has been a little different.. With the small SAN they ar fine.. Anything with a lot of nodes and Volumes/Storage they fall down….