Dasd concurrent maintenance for a pci based dasd subsystem

摘要

In an electrical system, concurrent maintenance of a system component coupled to the system by an adapter on a first communications path is accomplished through the provision of a second communications path to a system power controller, so that concurrent maintenance is not dependent on communications over the first communications path. In particular, concurrent maintenance of a direct access storage device (DASD - 404) coupled to a computer system through one of the small computer system interconnect (SCSI) buses (408), an input-output adapter (IOA - 402A), a peripheral component interconnect (PCI) bus (401), and a PCI bridge circuit (PCIB - 103), is enabled by providing a IIC serial, point-to-point signal path (104) between the bridge circuit (103) and a system power control network (SPCN - 102) to coordinate quiescing of the SCSI buses (408) and powering down of the DASD (404). <IMAGE>