With the Shark it is now possible for multiple IO's to be concurrently active on a given device at the same instant in time. If the IO requests originate from different hosts the feature which allows this is called Multiple Allegiance. If the IO requests originate from the same host the feature is called Parallel Access Volumes. Both of these features will allow multiple data set access on the same logical volume at the same time. Redundancy Reliability is another positive factor with the Shark.
Redundancy is built into the system so that data availability is maintained when a resource is lost.