I am reading swordfish specification which can manage multiple storage systems in an unified way. It regards storage system as a StorageService. The classofservice is managed under the StorageService. Administrator must create different classofservice for each of StorageService even though some StorageSerivces have the same capabilities. I am curious whether Swordfish support managing classofservice across StorageServices or not?
StorageService and StorageSystem are not the same at all.
The term StorageSystem refers to a compute platform that hosts one or more StorageServices. Note, that there is StorageSystem is not modeled in the Redfish/Swordfish schema. Rather, a StorageSystem is represented by a ComputerSystem that has its HostingRoles property set to StorageServer.
The term StorageService refers to a service that provides advanced storage management functionality. The StorageService has a relationship to its hosting system (see NavigationProperty HostingSystem). The hosting system can be a simple, or complex computing platform, which could be provided by a chip or a cloud. The hosting system can also be a front-end to a cluster. Regardless, the hosting system is represented by either a Computer System or a Storage Controller.
As currently defined each instance of a ClassOfServiceCollection is contained (i.e. part of) an instance of StorageService. However, Swordfish does not say where each individual instance of ClassOfService is contained.
All of this is a long-winded way of saying that so far, the decision of whether or not an individual ClassOfService can be referenced by more than one StorageService is left to the implementation.
That is certainly possible. You should propose to the feedback portal (https://www.snia.org/feedback) or if you are a member, to the SSM Technical Work Group (https://members.snia.org/wg/ssmtwg/dashboard) directly.