Abstract: One embodiment of the present invention provides a system that supports multiple versions of highly available objects. A highly available object is a primary object and one or more secondary objects. In an environment supporting multiple versions, the client, the primary, and the secondary objects can each be running either old or new software. Highly available objects introduce a need to process checkpoints where the primary and each of the secondary objects can be at different software versions. In one such situation, the system receives a change to a new version primary object at a node running new version primary software. Next, the system creates a new version checkpoint from this change and distributes the new version checkpoint to nodes executing new version software. The system also translates the new version checkpoint into an old version checkpoint and distributes this old version checkpoint to nodes executing old version software.

Abstract: A ruggedized file system, which provides ruggedness to non-volatile storage media at the device driver level. The ruggedized block device driver implementation provides ruggedness at the device driver level, thereby allowing atomic sequences of operations by the file system. Accordingly, the device driver is told that the current data state is a “fall-back” consistent state, into which the system should wake up if interrupted prior to completion of the sequence, following which operations are executed as required by the file system, including erasing, writing or overwriting blocks. The device driver is further told when the atomic sequence is complete, such that a new consistent state is thereby defined. It is, accordingly, the responsibility of the device driver to ensure that either the sequence completes and the file system reaches the target consistent state, or if power is lost or any other failure occurs in the middle, the file system will wake up in the initial fall-back state.

Abstract: A method of maintaining a hierarchy of application objects commences with the automatic detection of the exit of a process of a child application object in an unexpected manner. Responsive to the detected exit, a grandchild application object, launched by the child application object, is automatically terminated. An attempt is then made to restart the child application object. The outcome of the restart of the child application object is reported to a parent application object that launched the child application object.

Abstract: A method or system for supporting a computer systems self repair, including the computer executed steps for booting from a first boot device, and booting from a second boot device in response to a signal indicating a need for repair. While booted from the second boot device the computer system is capable of repairing software on the first boot device. The signal may effect a logical or physical switch. Repairing software may be performed in part by copying BIOS, template, backup or archive software from a device other than the first boot device. Repairing software may be performed automatically without direction by a user or according to preset preferences.

Abstract: A system and methods for carrying out maintaining a software configuration management system are disclosed. In particular, a way to reverse prior revisions without removing their history in the server are described. When a client submits an undo command to reverse the effects of one or more revisions within a stated revision range of a file, the revision history is updated by submitting a new revision that effectively removes the changes embodied within the range of undone revisions. The new method for implementing undoing prior revisions preserves the revision history for a file in case there is a need to access the undone revisions at a later time.

Abstract: The disclosed systems and methods provide for the protection of protected memory, for example, a hard disk, in a computer system. The systems and methods are configured to re-direct read and write access commands from locations in the protected memory to alternative storage locations. The systems and methods provide the ability for the user to accept or reject any BIOS changes that are to be made to the computing system. In addition, the systems and methods protect against operating system crash due to missing or corrupted files. The systems and methods are additionally operable to recover mistakenly deleted or damaged application data from a hard disk level, as well as to protect the operating system and data of the computing system against virus penetration. In other embodiments, the systems and methods are operable to provide for a security lock to the computing system and its associated data.

Abstract: The technique disclosed herein provides for simultaneously checkpointing all of the processes in a specified process group or family at the application level, and restoring those processes at a later time, optionally on a different machine, with the parent-child relationships restored intact. File descriptors that are shared among the processes at checkpoint time are restored to the family of processes such that the file descriptors are shared just as they were at the time of taking the checkpoint.

Abstract: A method and system for improving data migration from source data stripes to destination stripes in a Redundant Array of Independent Drives (RAID) logical drive migration (LDM). The invention describes a procedure for checkpointing data migrations, so that if the system should fail in the middle of the LDM, the computer can resume the LDM from the last checkpointed destination stripes, thus ensuring accurate tracking of data location. Further, the invention also provides the capability of properly checkpointing a data write to a stripe according to whether or not the stripe unit has been migrated previously.

Abstract: A storage device for a computer, combining an audit trail storage with (1) a connector adapted for connecting the storage device to a connection point of the computer, (2) a primary storage having first data stored thereon, and adapted for sending the first data to the computer in response to a corresponding read command received at the connection point, and (3) secondary storage adapted for storing second data in response to a corresponding write command received at the connection point and further adapted for sending the second data to the computer in response to a corresponding read command received at the connection point. The audit trail storage is adapted for recording a log of communication activity occurring at the connection point.

Abstract: A method and system for reducing overhead associated with recovering after a failure. According to the method, a checkpoint value is maintained that indicates which records of a plurality of records have to be processed after the failure. The plurality of records contain change information that corresponds to a plurality of data blocks. A target checkpoint value is determined based on a desired number of data block reads that will be required during a redo phase of recovery. Changes contained in volatile memory are then written to nonvolatile memory to advance the checkpoint value to at least the target checkpoint value.

Abstract: Disclosed are a method, apparatus, and computer program for, in an end-user computer environment, reversing an effect of an autonomously-initiated program action, by recognizing that the program action is to be performed, recording data representing a state change caused by the program action, providing a user option to cause the computer system to reverse the state change caused by the program action, responsive to a user selection of the user option, retrieving the data representing a state change, and reversing the state change caused by the program action.

Abstract: A method and system allows multiple compute elements to independently read and clear error register logs, discard invalid data and ensure that a user receives information stored in error log registers. Error log registers are not cleared until its information is successfully retrieved by a compute element. A counter maintains a count of errors for which detailed error information has been lost.

Abstract: A method and system for intelligent trap analysis for debugging software on a computer system. Instead of dumping only a register context snapshot or all of memory to a file, a trap handler determines a likely cause of a trapped instruction and selects relevant memory addresses for copying to a file. The relevant memory addresses and their contents are preserved for later analysis. The trap handler may step back through the process instruction list searching for relevant memory addresses referenced by the instructions preceding the trapped instruction. The module may undo the effect of instructions as it steps back through the instruction list.

Abstract: The present invention is directed to a method and mechanism for accessing recovery log information in a database system. The data stored in the recovery log is presented as a relational database “view,” which can be queried and accessed using relational database statements even though the underlying recovery log data may be stored in a non-relational format. According to an aspect of the invention, the recovery log data is thus encapsulated by the view presented to users of that data.

Abstract: A method for diagnosing faults in a computer-based system. A log of errors of different kinds that have been recorded in the system is read, and errors of those kinds that are relevant to one or more predetermined types of faults that can occur in the system are selected from the log. The selected errors are filtered so as to compose one or more events, each event comprising one or more occurrences of one or more of the relevant kinds of the errors. The composed events are analyzed to reach an assessment that at least one of the predetermined types of faults has occurred.

Abstract: A computer comprises a write monitor unit for monitoring a data write operation into an operating system file, an update data file for storing update data upon detection of a data write operation, an update-log file for storing the history information for the update data in the case where the update data is stored, and a read monitor unit for reading data from the update data file in the case where the history information for the data to be read from the operating system file is stored and reading data from the operating system file in the case where the history information is not stored.

Abstract: Disclosed is a method for preventing ghost writes in a multi-computer system. A first computer in the multi-computer system issues one or more write requests to a storage device, each write request normally being effectuated after being pending for a time. The method generally comprises the steps of detecting a condition indicative of a failure associated with the first computer and preventing the effectuation of write requests issued by the first computer to the storage device and pending at the time of the detected condition. In one embodiment, the condition indicative of a failure associated with the first computer comprises at least one of the group consisting of a reduction in the number of known operating computers in the multi-computer system, and a state change of a volume group associated with the computer on the storage device from inaccessible to accessible and a reduction in the number of known operating computers in the multi-computer system.

Abstract: A data processing system and method that provides checkpointing and permits a continuous flow of data processing by allowing each process to return to operation after checkpointing, independently of the time required by other processes to checkpoint their state. Checkpointing in accordance with the invention makes use of a command message from a checkpoint processor that sequentially propagates through a process stage from data sources through processes to data sinks, triggering each process to checkpoint its state and then pass on a checkpointing message to connected “downstream” processes. This approach provides checkpointing and permits a continuous flow of data processing by allowing each process to return to normal operation after checkpointing, independently of the time required by other processes to checkpoint their state.

Abstract: A primary computer system has a database, application programs that modify the local database, and a transaction manager that stores audit records in a local image trail reflecting those application program modifications to the local database. In a remote backup system, a Receiver process receives audit records from the primary system. The audit records include audit update and audit backout records indicating database updates and database backouts generated by transactions executing on the primary system. The Receiver stores the audit update and audit backout records in one or more image trails. For each image trail there is an Updater process that applies to a backup database volume the database updates and backouts indicated by the audit update and audit backout records in the image trail.

Abstract: In a transaction processing method for executing a series of a plurality of transactions in accordance with a workflow, compensation processing is registered as an error recovery flow when each transaction is executed, the compensation processing executing error recovery processing when an error occurs while the transaction is executed, and a series of compensation processing is executed in parallel in accordance with the registered error recovery flow when an error occurs while any of the transaction is executed.

Abstract: A programming environment can be modified to provide automatic support for reverting program memory states. Such memory reversions are used to provide automatic support for undo, redo, and abort operations for application programs written with the programming environment. Memory allocation code (e.g., functions, procedures, etc.) are modified to mark allocated memory as protected, and an exception handler is assigned to such memory. Attempts to access the memory cause an exception to be generated. This exception is caught, providing opportunity for the memory to be preserved before it is modified. Previous memory states can be retrieved by restoring such stored memory states.

Abstract: Audit Trail recovery is enhanced by including addresses of immediately prior periodic saves of all active or open Steps or transactions in each new period save area. Reduced cost in main memory usage and on-the-fly processing to accomplish audit trail format that enhances recovery time results from ability to immediately address next prior period save data once a last periodic save is found in reading back the audit trail. Reading back the audit trail to find the last periodic save can be avoided too by directly addressing the last periodic save in preferred embodiments since the computer system will in all events temporarily maintain a record of the address of the last periodic save to record the next time a periodic save is to be made, so this temporarily maintained record can be accessed and used to jump directly to the last periodic save address on the audit trail.

Abstract: Information regarding the operating conditions of a computer system is stored in a storage which is dedicated to a failure management system. The storage is updated with the current operating conditions either periodically or upon the occurrence of predetermined events. When a first failure identification mechanism identifies a failure in the computer system, a capture mechanism interrupts the updating of the storage leaving information regarding operating conditions which contributed to the failure in the storage. This latter information can then be read out to aid in diagnosis of the failure. Since the operating condition information is stored in a dedicated storage, the information is not modified by events that take place after the failure is identified. In accordance with one embodiment, the computer system ordinarily holds state and other operating information in a set of storage devices, such as, for example, state registers.

Abstract: A method and computer program for reducing the restart time for a parallel application are disclosed. The parallel application includes a plurality of parallel operators. The method includes repeating the following: setting a time interval to a next checkpoint; waiting until the time interval expires; sending checkpoint requests to each of the plurality of parallel operators; and receiving and processing messages from one or more of the plurality of parallel operators. The method also includes receiving a checkpoint request message on a control data stream, waiting to enter a state suitable for checkpointing, and sending a response message on the control data stream.

Abstract: If an incidental interruption of power supply occurs in a system, an apparatus and method is provided that a status immediately before the interruption of power supply can be stored. A request for a status-storing process is outputted from an application to a check point manager in a module. A request for an execution of a snap shot output to components, such as the application, a device driver and the like, is outputted to the manager. A sequence at this time is based on an sequence recorded in a status-storing database. The sequence represents a dependence relation between the components. When each component receives the request for the snap shot output, a function existing in a particular address for each component is read out and the component status is outputted as a snap shot file through the manager to a non-volatile memory.

Abstract: In one embodiment a multiprocessing apparatus includes a first processor and a second processor. Each of the processors have their own data and instruction caches to support independent operation. In a normal mode the processors independently execute separate instruction streams. Each of the processors has a respective signature generator. The system also includes a compare unit coupled to the signature generators. In a high reliability mode, both processors execute the same instruction stream. That is, each processor computes a version of a result for ones of the instructions in the stream. Responsive to the respective versions, the respective signature generators assert signatures to the compare unit, so that a faulting instruction may be detected. In another aspect, each processor has its own respective commit logic.

Abstract: In a time-versioned storage mechanism, data is stored as a plurality of records, each including at least one attribute, a time span indicating the time span for which the attribute is valid, an insertion time indicating when the record was created, and a type field. The type field indicates whether the record is a concrete record, a delta record that possibly modifies the attribute value of a previous concrete or delta record, or an archive record replacing one or more records that have been archived. The data is accessed to find an attribute value from the point of view of a specified viewpoint time, by retrieving only records with insertion times not later than said viewpoint time, and constructing an attribute value from the retrieved records. The data is updated only by adding concrete records or delta records, without modifying attribute values in the concrete records or delta records.

Abstract: A replica system and a method of producing a replica are provided for dealing with a database management system including both database programs and files. The system transmits and receives data between interfaces using a common data format, by including a replica manager which receives a replica instruction and determines an object to be read from a master database and an object to be written in a copy database, according to the replica instruction. By giving a command to the database management system, data associated with the object to be read is read from the database, and data format is converted into a standard data format. The received data is then converted to data format associated with the object to be written, and the converted data is finally stored in the copy database.

Abstract: A method and system wherein participant node lists are maintained for each individual transaction. In addition, local nodes maintain participant node lists and provide same to coordinating nodes under certain circumstances. The coordinating nodes merge participant node lists and selectively utilize the lists to minimize message duplication. Further, connection node lists for each application are maintained at coordinating nodes and are utilized for application rollback procedures.

Abstract: A transaction processing method, system and computer program product for processing applications comprising multiple component transactions. A transaction failure of a component transaction causes a reliable admission of failure by means of a failure indicator to be made available to one or more further transactions. The failure indicator is stored in recoverable storage, so that its effect can survive system failure and recovery.

Abstract: A method and apparatus for removing changes made by a particular transaction is provided. According to one aspect, two or more sets of changes that were made by a particular transaction that can be removed in parallel are identified. A corresponding recovery process is assigned to each of the two or more sets of changes. Using the corresponding recovery process, the changes identified in each of the two or more sets of changes are undone in parallel.

Abstract: In a storage system having a plurality of disks arranged in a RAID array with one of the disks failed, a method of reorganizing the data on the RAID array at the time of failure to prevent both a decrease in performance of the array and reliability of the data and an increase in the cost of operation. Data from the failed disk is regenerated one strip at a time and written onto the original parity chunk for the strip. The resulting fully folded array has the characteristics of a RAID level 0 array. When a replacement disk is inserted into the array the process is reversed to bring the fully folded array back to a fully redundant condition.

Abstract: A method and system are provided for maintaining a checkpoint value that indicates which records of a plurality of records associated with updates made before a failure have to be processed after the failure. According to one aspect of the invention, an ordered list of buffers is maintained in volatile memory. The ordered list of buffers has a head and a tail. The ordered list of buffers is maintained by writing a record that indicates the update to nonvolatile memory and adding the buffer to the tail of the ordered list whenever an update is made to a data item within a buffer in volatile memory. When a data item contained in a buffer within the ordered list is stored in nonvolatile memory, the buffer can be removed from the ordered list. A checkpoint value that identifies a record associated with a buffer located at the head of the ordered list is written to nonvolatile memory. According to another aspect, after a failure, the record associated with the checkpoint value is identified.

Abstract: A system and method for conducting secure fault tolerant transactions, such as financial transaction, remotely is disclosed. The transactions are conducted utilizing a portable processor device which is initialized and authorized according to the present invention. Thereafter, the portable processor operates to conduct transactions involving information exchange through unsecured communication paths according to a predetermined protocol. The protocol includes the use of atomic transactions within the portable processor device.

Abstract: A method and apparatus to provide DBMS restart recovery that allows transactions to access data that does not have restart recovery work pending. Access to data requiring restart recovery work to be performed is restricted, and a transaction is denied access to this data. In another embodiment, the invention allows certain transactions to access restricted data that has restart recovery work pending. These transactions are transactions that do not require data consistency. Regardless of the embodiment, the invention allows full recovery to be completed concurrent to the processing of new transactions requiring access to the database. An amount of restart recovery processing may be postponed until after the DBMS has begun accepting new work requests.

Abstract: An information processing apparatus manages the correspondence between identification information, which is for identifying a plurality of transactions within one process, and the transactions. To this end, the information processing apparatus operates on the identification information by operations including creation, cancellation and switching of the identification information. The creation, cancellation and switching of the identification information then results in the corresponding operation on the respective transaction.

Abstract: The present invention is a process-pair resource manager for use in a transaction processing system. The process-pair resource manager includes a concurrent aspect and a serial aspect. The concurrent aspect provides an object-like interface to a protected resource. An application program participating in a transaction accesses the protected resource by passing messages to the concurrent aspect. The concurrent aspect adds a description of each message as well as the result of processing each message to a transaction record. At the conclusion of a transaction, the concurrent aspect passes the transaction record to the serial aspect. The serial aspect then replays the transaction, using the transaction record. If the replay of the transaction is consistent with the transaction as recorded in the transaction record, the serial aspect sends a message to the concurrent aspect voting to commit the transaction. In turn, the concurrent aspect sends a message to the transaction manager forwarding the commit message.

Abstract: A novel checkpoint acquisition accelerating apparatus is disclosed. When data are updated on a cache memory, a before-image acquiring section acquires the update address and the previous data and stores them in a before-image storing section. A cache flush executing section issues to a system bus a bus command requesting the contents of the updated cache block to be written-back to a main memory using all the addresses stored in the before-image storing section. A main memory restoring section, on the other hand, issues bus command requesting all the previous data stored in the before-image storing section to be updated and written in the main memory on last-in first-out basis. As a result, a checkpoint acquisition accelerating apparatus is realized which is capable of easily realizing the checkpoint and recovery function in a computer including at least a standard uniprocessor.

Abstract: A transaction log stored in a first memory is posted to one of two separate log areas, selectively, on a storage system having a plurality of storage media such as disk drives. Posting occurs to a "disk log" area when a page-full status of the first memory transaction log is detected. Alternatively, when a posting request occurs before a page-full status of the transaction log has been detected, then posting occurs immediately to a least busy disk of a "staging log" area. Posting occurs to the least busy disk of the "staging log" area by circumventing normal storage system data management and redundancy techniques such that data in the staging log area is not kept redundantly on the storage media. Rather redundancy is maintained by the fact that the transaction log remains with the first memory in addition to being copied to the staging log area. The staging log area includes reserved space on each of the plurality of storage media and is divided into logically separate portions on each of the storage media.

Abstract: A method and apparatus for using undo/redo logging to perform asynchronous updates of parity and data pages in a redundant array data storage system is disclosed. The computer-implemented apparatus includes, 1) a redundant array data storage system having a plurality of data pages and a corresponding parity page residing therein, each page of the plurality of data pages and the parity page containing version information indicating a version of content in the page, 2) a memory-resident plurality of data pages corresponding to the plurality of data pages residing in the redundant array data storage system, 3) a data log retaining modification information defining any differences between content of the memory-resident plurality of data pages and content of the plurality of data pages residing in the redundant array data storage system, and 4) control logic for deferring modification of the parity page following modification of one of the plurality of data pages.

Abstract: When an I/O request block is received from a file system, a number-of-system's-failures setting section stores the present number of failures in the I/O request block, and hands over the I/O request block to a software driver after taking a checkpoint. When the I/O request block is received from the software driver, a number-of-failures determining section determines whether or not the number of failures stored in the I/O request block coincides with the present number of failures. If they do not coincide, an I/O request error return section will return the I/O request block to the software driver without handing over it to a device driver and causes an I/O request completion processing section to reissue the I/O request block again.

Abstract: A scheme for restarting processes at distributed checkpoints in a client-server computer system, in which a fault in one client computer does not affect the server computer and the other client computers. In this scheme, a fault occurring in one computer among of a plurality of computers constituting a client-server computer system is detected while these plurality of computers are executing respective processes, and whether that one computer in which the fault is detected is a server computer or not is judged. Then, related processes executed on these plurality of computers are restarted when that one computer is judged as the server computer, whereas no process executed on these plurality of computers is restarted when that one computer is not judged as the server computer.

Abstract: The present invention relates to a recovery function from a system failure such as a power failure and a media failure such as a breakage of disk at a transaction processing system of a plurality of user environment, and is applied in carrying out a checkpoint to reduce an amount of work required for failure recovery, and particularly to a fuzzy checkpoint method which is a method of enhancing a system performance by not interrupting other transactions ever for a moment at the time of checkpoint. According to the present invention, the occurrance of dangling transaction is prevented by deleting the corresponding transaction entry from the transaction table during performing of the redo step, for the transactions terminated between the point of time when the checkpoint start log record of the last completed checkpoint is logged and the point of time when the checkpoint end log record is logged.

Abstract: Managing a log stream of a computer system. An entry of a log stream, desired to be removed from the log stream, but not eligible for removal, is logically deleted. Logical deletion keeps the entry on the log stream and indicates that the entry can be removed from the log stream when it is eligible. When the entry is eligible, it is removed. If a desired entry remains at the tail of the log stream for a given period of time, thus not allowing the removal of one or more undesired entries, the desired entry is rewritten to the head of the log stream and deleted from the tail. Thereafter, other logically deleted entries eligible for deletion are removed from the log stream.