International Business Machines Corporation

Alden B Johnson

James T Brady

Steven D Gerdt

Norman Apperley

Jaishankar Moothedath Menon

Shin-Yuan Tzou

John Chi-Shing Lui

Paul T Burton

Predictive failure analysis of a storage subsystem is efficiently conducted and data quickly recovered from a failed Read operation. This may be implemented in a storage system including a host coupled to a supervising processor that couples to a parity-equipped RAID storage subsystem having multiple HDAs each including an HDA controller and at least one storage medium. In one embodiment, when an HDA experiences an error during a Read attempt, the HDA transmits a recovery alert signal to the supervising processor; then, the processor and HDA begin remote and local recovery processes in parallel. The first process to complete provides the data to the host, and the second process is aborted. In another embodiment, an HDA's PFA operations are restricted to idle times of the HDA. A different embodiment limits HDA performance of PFA to times when the processor is conducting data reconstruction. Another embodiment monitors HDA errors at the supervisory processor level, initiating an HDA's PFA operations when errors at that HDA have a certain characteristic, such as a predetermined frequency of occurrence.

Efficient system for predicting and processing storage subsystem failure

A system for managing data storage devices of a data storage subsystem. A data storage system includes a controller coupled to multiple data storage devices. In response to a request, the controller allocates the devices' storage space into a number of storage partitions or 'virtual devices.' The request specifies the size and function mode for each storage partition. Each storage partition, having the requested size, is operated according to its requested function mode. This involves mapping access commands, which specify virtual addresses, to the proper physical addresses of the appropriate data storage devices.

Reconfigurable data storage system

A method and means are disclosed in a Log Structure Array (LSA) storage subsystem for managing said subsystem without a need for an access to a complete LSA directory in a RAM. This object is achieved by maintaining (1) a subset of the LSA directory (referred to as LSA sub-directory) in a RAM where the LSA sub-directory comprises the logical track address of a predetermined number of most recently accessed logical tracks; (2) a journal of changes to the LSA directory which is maintained on a different power boundary than the LSA directory power boundary; and, (3) an array of bit maps, one bit map per segment which is used for fast garbage collection thus eliminating the need for having an access to a complete LSA directory in a RAM during garbage collection.

Log structured array storage subsystem using LSA directory and LSA

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Los Gatos, CA, United States of America

Alden B Johnson