Abstract: A technique for handling hardware errors in a computing system, such as a data storage facility, while avoiding a system crash. An interface is registered with an operating system of the computing system to process hardware errors. When a hardware error is detected, the interface checks an error register to identify the adapter that likely causes the error, and quarantines, e.g., blocks off, the offending adapter from the computing system. The interface then notifies the operating system that the error has been handled, thereby causing the operating system to bypass a system crash that would otherwise occur. The interface can be provided as a kernel extension of a device driver associated with the operating system.

Abstract: A method of enabling state save and debug operations for co-routines for first failure data capture (FFDC) in an event-driven environment. A stack management utility allocates space for a context structure, which includes a state field, and a stack pointer in a buffer. A context management utility initializes a first context structure of a first co-routine and saves a state of the first context structure in response to an execution request for a second co-routine. The context management utility sets a second context structure as a current context. When execution of the current context is complete, the context management utility restores the first context structure of the first co-routine as the current context. If the state field is not set to a valid value, a state save function “state saves” all allocated co-routine stacks and context structures, restores the entire system to a previous valid state, and restarts operations.

Abstract: An instruction capable of preventing incorrect usage of ucontext functions in a multi-process environment is disclosed. During an execution of a setcontext instruction, a determination is made whether or not a contextID of a context structure associated with a next context indicates that it is an original context of a process. If the contextID of the next context structure is an original context of a process, another determination is made whether or not the contextID of the context structure associated with the next context is the same as the original contextID of the process. If the contextID of the context structure associated with the next context is not the same as the original contextID of the process, an error recovery routine is invoked.

Abstract: A method and means within a hierarchical, demand/response DASD subsystem of the passive fault management type in which, upon the occurrence of fault, error, or erasure, a long device busy signal of finite duration is provided to a host CPU. Any DASD storage device subject to the anomaly is isolated from any host inquiry during this interval. These measures permit retry or other recovery procedures to be implemented transparent to the host and the executing application. This avoids premature declarations of faults, errors, or erasures and consequent host application aborts and other catastrophic measures. If the detected anomaly is not resolved within the allotted time, then other data recovery procedures can be invoked including device reset, the status reported to the host, and the next request processed.

Abstract: A system and method for changing the number of logical volumes in a drawer in a rack in a direct access storage device subsystem is disclosed. The method and system are able to change the number of logical volumes without disrupting access to the other logical volumes in the rack. Channel connection addresses, which are logical volume addresses as known by the CPUs, are freed by removing the old drawer and then are mused. If the new drawer has more logical volumes than the old drawer, the next unused channel connection addresses are used with the new drawer. In a subsystem having a storage controller for providing control for a plurality of direct access storage devices, the logical volumes are spread across multiple physical devices. The storage controller maintains configuration data for the entire subsystem in redundant, non-volatile storage locations reserved specifically for its use.

Abstract: An adaptive hierarchical cache management system for improving effective cache hit ratios by eliminating unnecessary duplicate cache entries in two coupled cache memories. When a cached Storage Controller (SC) is coupled to a Cached Storage Drawer (CSD), the hierarchical coupling of the SC cache memory and CSD cache memory unnecessarily duplicates cache entries during normal operation. A Conditional Purge procedure purges duplicate lines from the CSD cache subject to a DASD activity threshold. A Prenotify Intent parameter allows the SC to request restaging of the purged cache entry preparatory to fast write or LRU demotion in the SC cache. The new procedures substantially and transparently improve the combined caching efficiency without significant new hardware or software overhead.

Abstract: A method and system for enhancing the efficiency of communication between multiple direct access storage devices and a storage system controller in a data processing system. In a data processing system having a storage system controller connected between a plurality of host computers and a plurality of storage devices, a processors, within the storage system controller, is provided for controlling the storage devices. Commands and data are communicated between the processor and the storage devices over a communication channel. An independent polling mechanism is provided which is coupled to the communication channel and the processor. The independent polling mechanism is utilized for collecting and storing interrupt status data from each of the storage devices.

Abstract: A method and system for enhancing the efficiency of data accessing within a storage subsystem which is coupled to a host system via a storage subsystem controller and a data channel. The storage subsystem controller preferably includes a tracked cyclic storage device which has multiple disks which are rotatable about a single spindle. Recording tracks within each disk are then accessed utilizing multiple switchable transducer heads. A signal transmitted from the host system is utilized to define a sequence in which a group of recording tracks are to be accessed. That signal is then utilized to create a transducer head switching table within the storage subsystem controller which lists each recording track to be accessed and an associated control parameter for selecting a particular transducer head to be utilized to access a subsequent recording track.