Abstract: A computer implemented method on a computer readable media is provided for determining the source of a problem in a complex system of managed components based upon symptoms. The problem source identification process is split into different activities. Explicit configuration non-specific representations of types of managed components, their problems, symptoms and the relations along which the problems or symptoms propagate are created that can be manipulated by executable computer code. A data structure is produced for determining the source of a problem by combining one or more of the representations based on information of specific instances of managed components in the system. Computer code is then executed which uses the data structure to determine the source of the problem from one or more symptoms.

Abstract: A method of improving the performance of a storage system is provided. The method includes sending a pre-request to a logical device before data associated with the previous request is transferred from a cache to the requesting host device. Additionally, while a host controller of the storage system is transferring data from the cache to the requesting host, it will also check to see if any other requests are entered in a request queue for that logical device. To do this, the host controller checks a status flag in a mailbox location within the host controller. A disk controller is also responsive to the placement of requests in the mailbox location and can set the status flag upon a completion of a data transaction. If there has been an entry, a pre-request will be sent to the logical device while the data from the previous request is being transferred to the host.