International Business Machines Corporation

Martin Taubert

Kenneth J Oakes

John S Trotter

Janet R Easton

Joachim Von Buttlar

Andrew W Piechowski

Muruganandam Somasundaram

Andreas Kohler

Karthik Bhat

Naveen Kumar Hullahalli Rajashekar

Ulrich Helmich

Ankur Agrrawal

Clarence D'Mello

Donald W Schmidt

Jerry Wayne Stevens

Robert Edward Galbraith

Alexandra Winter

Francis Gassert

Elke G Nass

Ambrose Verdibello

Robert M Whalen, Jr

Jana Christine Migge

Embodiments of the present disclosure provide systems and methods for implementing enhanced Device Control Block (DCB) scan recovery for channel recovery actions. A disclosed method comprises identifying channels to be recovered and creating a DCB bit array reflecting each DCB to be scanned for the set of the channels to be recovered by a system assist processor. The system assist processor performs asynchronous channel communication area (CCA) recovery processing, starts synchronous DCB scan recovery, and sequentially processes an incremental portion of the DCB bit array interleaved with asynchronous CCA recovery processing. The system assist processor completes asynchronous CCA recovery processing and synchronous DCB scan recovery to complete channel recovery of the set of channels. The system assist processor starts each channel of the set of channels responsive to completing channel recovery processing for each channel.

Device control block scan for channel recovery actions

An approach for recovering event logs. The approach detects corruption in an event log. The approach determines whether a start pointer in a log buffer header is corrupt. Responsive to a determination that the start pointer is corrupt, the approach recovers the start pointer. The approach determines whether an end pointer in the log buffer header is corrupt. Responsive to a determination that the end pointer is corrupt, the approach recovers the end pointer. The approach determines whether an eye catcher in the log buffer header is corrupt. Responsive to a determination that the eye catcher is corrupt, the approach recovers the eye catcher. The approach presents one or more log entries to a management console.

Recovery of first failure data capture logs

A computer implemented method for sharing physical memory among logical partitions. A computer reserves physical memory of a Central Electronic Complex (CEC) for communication within the CEC as a shared memory pool. The computer creates a first logical partition using resources of the CEC that are not reserved as the shared memory pool. The computer creates a second logical partition using resources of the CEC that are not reserved as the shared memory pool. The computer creates a virtual local area network (VLAN) having at least two addresses within the CEC. The computer allocates a portion of the shared memory to the VLAN as the shared memory pool.

Physical memory shared among logical partitions in a VLAN

Disclosed are a method and system of tracking real time use of I/O control blocks on a processing unit basis, in a multiprocessing system, such that in the case of a processing unit failure, a list accurately and concisely identifies the control blocks that need to be recovered. This eliminates the need to scan all the I/O control blocks, greatly reducing the overall system recovery time and minimizing impact to the rest of the running system. The preferred embodiment of the invention uses a task control block structure to record which I/O control blocks are in use by each Processing Unit. Also, the lock word structure defined in the I/O control blocks is provided with an index back into the task control block to facilitate managing the task control block entries.

Method and system for state tracking and recovery in multiprocessing computing systems

Disclosed are a method and system for parallel execution of recovery in a non-homogeneous multi-processor environment. The method defines criteria how to decide which recovery actions are to be performed, and on which processor. If multiple recovery actions are pending, the goal is to execute them in parallel on multiple processors. This is much more efficient than the traditional approach of one processor doing all the required recovery. In addition, in large, non-homogeneous systems such a single processor capable of doing the complete recovery might not be existing at all due to technical limitations. The method of this invention also defines rules and mechanisms how multiple processors executing recovery in parallel can access shared resources while avoiding deadlock situations. This includes accessing resources that are currently owned by another processor.

Method and system to execute recovery in non-homogenous multi processor environments

Disclosed are a method and system for detecting errors in a computer system including a processing unit to perform tasks to change items. The method comprises the steps of assigning a task control block to the processing unit, and using the task control block to keep track of items being changed by the processing unit. The method comprises the further steps of at defined times, checking the task control block to identify items being changed by the processing unit, and checking the states of said identified items to determine if those states are correct. The preferred embodiment of the invention detects an error when it arises (where possible), and utilizes an infrastructure that allows simple and periodic consistency checks (for example, at designated code points) that detect the error before it causes follow-on problems.

Method and system to detect errors in computer systems by using state tracking

Method and system to execute recovery in non-homogeneous multi processor environments

Disclosed is a method for detecting errors in a computer system including a processing unit to perform tasks to change items. The method comprises the steps of assigning a task control block to the processing unit, and using the task control block to keep track of items being changed by the processing unit. The method comprises the further steps of at defined times, checking the task control block to identify items being changed by the processing unit, and checking the states of said identified items to determine if those states are correct. The preferred embodiment of the invention detects an error when it arises (where possible), and utilizes an infrastructure that allows simple and periodic consistency checks (for example, at designated code points) that detect the error before it causes follow-on problems.

Method to detect errors in computer systems by using state tracking

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Gaertringen, Germany

Martin Taubert