Patent ID: 6529944
Filing Date: 2003-03-04
Classification: G06F,Y10S

Abstract:
In a system comprising a local mass storage system which is linked to a host system and to a physically remote mass storage system, the physically remote mass storage system being linked to one or more other physically remote mass storage systems so as to form a stream of mass storage systems, each pair of mass storage systems being linked by a communications path and a pair of remote link directors, each of the mass storage systems comprising one of the pair of remote link directors, and each such mass storage system further comprising a cache memory, a disk adapter and one or more disk drives, a host system providing local control of mass storage volumes located on the local mass storage system and remote control of linked mass storage volumes located on any of the remote mass storage systems in the stream of mass storage systems, comprising:a mechanism at the host system that generates and issues a user-specified command from the host system to a local mass storage system; a selected identifier being in the command as issued from the host system, the command being recognizable by each mass storage system in the stream of mass storage systems, the selected identifier being selected from a group of identifiers, the identifiers in the group identifying the mass storage systems in the stream of mass storage systems, each mass storage system that is not identified by the selected identifier being configured to forward the command to another mass storage system, at least one mass storage system that is identified by the selected identifier being configured to execute the command after the at least one mass storage system receives the command, a plurality of user-specifiable parameters also being specifiable in the command as issued from the host system, the parameters that may be specified in the command including a first parameter, a second parameter, and one or more third parameters, the presence of the first parameter in the command indicating that the command is to be executed physically remotely from the local mass storage system, the second parameter indicating an order in which the command is to be executed, and the one or more third parameters indicating one or more paths via which the command is to be forwarded to the at least one mass storage system, the absence of the first parameter from the command indicating that the command is to be executed at the local mass storage system.