Storage vendors typically implement APIs for their products to provide management interfaces, but these APIs are proprietary, and interoperability between storage hardware and management applications depends on vendors agreeing to license each others’ APIs.
Examples of this type of arrangement include:
HP and IBM have mutually licensed each others’ API and CLI interfaces to enable HPs OpenView SAM to manage IBM Shark Enterprise Storage Servers, and IBM's Tivoli platform and Storage Software Group products to manage HPs StorageWorks EMA and EVA arrays.
IBM has traded APIs with HDS. HP has traded APIs with EMC and HDS.
While API exchanges help fill the standards gap, they are one-of-a-kind relationships that do not provide the universal interoperability and stability that users demand.