Hard partitioning is a physical separation of computing resourcesby hardware-enforced access barriers. It is impossible to read orwrite across a hard partition boundary, and there is no resourcesharing between hard partitions.
Soft partitioning is a separation of computing resources bysoftware-controlled access barriers. Soft partitions (subpartitionsin some contexts) enable the sharing of hardware resources amongseveral operating systems. Read and write access across a soft partitionboundary is controlled by the operating system or applications.OpenVMS Galaxy is an implementation of soft partitioning.
How customers choose to partition their new AlphaServer ESor GS series systems depends on their computing environments andapplication requirements. When planning for partitioning, the amountof memory required by the applications and which operating systemto run should be considered. When deciding how to configure an OpenVMSsystem that supports partitioning, look at the following questions:
How many hard partitions do I need?
How many soft partitions do I need?
How small can I make the partitions? Multiple hard partitions provide the maximum hardware securitybetween partitions. A single soft partition running in a hard partitionis equivalent to its running in a dedicated machine.
Multiplesoft partitions within a given hard partition allow sharing resourcessuch as CPUs and memory, and provide performance advantages.
HP OpenVMS Alpha Partitioning and Galaxy Guide
Managing Workloads With Partitions