Abstract: Registering a client with a distributed service. A method may be practiced, for example, in a network computing environment including a client at a local site and a number of distributed services at a number of remote sites. The method includes pinging one or more distributed services at one or more remote sites. A message is received from a distributed service from among the one or more distributed services. The message specifies an optimal remote site. The method further includes registering with a distributed service at the optimal remote site.

Abstract: A new schema implementation enables reversible changes to be made to definitions in a schema. The definitions of attributes and classes are in the form of schema objects. Each schema object has an internal ID in addition to its unique name and object ID (DID), and a deactivation flag for indicating whether the schema object has been deactivated. To modify an attribute or class, the corresponding schema object is deactivated by setting its deactivation flag to “TRUE,” and a new schema object is created to contain the changes. The new schema object has the same unique name and DID as the old schema object but is given a different internal ID. When a client wants to access instances of the schema object by its unique name or DID, a translation is made to provide the internal ID of the new schema object such that instances of the new schema object are located instead of the old schema object.

Abstract: An improved scalability testing architecture for distributed applications allows testing of scalability with respect to a given number of computers using a test network having only a small fraction of that number of computers. Each client computer in the test network hosts multiple bootable systems in bootable partitions which timeshare the host machine on a mutually exclusive basis. A launcher in each bootable system verifies scheduling information for an instance of an application under test residing in the same partition and either permits or prevents continued operation of the instance based on the scheduling information. If continued operation is to be prevented, the launcher triggers a boot next routine to exit and cede control of the computer to the next bootable system on the computer.

Abstract: A new schema implementation enables reversible changes to be made to definitions in a schema. The definitions of attributes and classes are in the form of schema objects. Each schema object has an internal ID in addition to its unique name and object ID (OID), and a deactivation flag for indicating whether the schema object has been deactivated. To modify an attribute or class, the corresponding schema object is deactivated by setting its deactivation flag to “TRUE,” and a new schema object is created to contain the changes. The new schema object has the same unique name and OID as the old schema object but is given a different internal ID. When a client wants to access instances of the schema object by its unique name or OID, a translation is made to provide the internal ID of the new schema object such that instances of the new schema object are located instead of the old schema object.

Abstract: A new schema implementation enables reversible changes to be made to definitions in a schema. The definitions of attributes and classes are in the form of schema objects. Each schema object has an internal ID in addition to its unique name and object ID (OID), and a deactivation flag for indicating whether the schema object has been deactivated. To modify an attribute or class, the corresponding schema object is deactivated by setting its deactivation flag to “TRUE,” and a new schema object is created to contain the changes. The new schema object has the same unique name and OID as the old schema object but is given a different internal ID. When a client wants to access instances of the schema object by its unique name or OID, a translation is made to provide the internal ID of the new schema object such that instances of the new schema object are located instead of the old schema object.

Abstract: Inconsistencies between cache and memory in a memory system operating in a computer are traced and corrected. A cache entry is checked against a counterpart memory entry to trace inconsistencies between the cache entry and the memory entry and to correct the cache entry. A page table entry in memory with a zero mapping mark is checked against a counterpart page entry in a translation lookaside buffer. Inconsistencies between the page table entry with a zero mapping mark and the existence of a counterpart page entry in the translation lookaside buffer is traced. The inconsistency is corrected by deleting the counterpart page entry in the translation lookaside buffer. Address mapping is checked comparing a page entry in the translation lookaside buffer against a counterpart page table entry in the memory. Inconsistencies between the page entry and the page table entry are traced and corrected.

Abstract: A new file system partition is added to an existing partition in disk storage space by creating a new file in the existing storage space of the existing partition and giving this file the attributes of a partition. This new file having partition attributes is referred to as a "raw file." Apparatus in a computing system for creating and accessing a raw file would comprise a storage system controller for creating a raw file of a predetermined size with the attributes of a partition, a storage space driver for accessing storage space in a data storage system and a storage access control for translating an access request for a raw file to an actual address for the raw file so the storage space driver can access the raw file based on the actual address for the raw file.

Abstract: A single transaction technique for a journaling file system of a computer operating system in which a single file system transaction is opened for accumulating a plurality of current synchronous file system operations. The plurality of current synchronous file system operations are then performed and the single file system transaction closed upon completion of the last of the file system operations. The single file system operation is then committed to a computer mass storage device in a single write operation without the necessity of committing each of the separate synchronous file system operations with individual writes to the storage device thereby significantly increasing overall system performance. The technique disclosed is of especial utility in conjunction with UNIX System V based or other journaling operating systems.

Abstract: A new file system partition is added to an existing partition in disk storage space by creating a new file in the existing storage space of the existing partition and giving this file the attributes of a partition. This new file having partition attributes is referred to as a "raw file." Apparatus in a computing system for creating and accessing a raw file would comprise a storage system controller for creating a raw file of a predetermined size with the attributes of a partition, a storage space driver for accessing storage space in a data storage system and a storage access control for translating an access request for a raw file to an actual address for the raw file so the storage space driver can access the raw file based on the actual address for the raw file.

Abstract: A method for verifying a desired operation of an untrusted memory device is performed under load and includes shadowing read and write operations to the untrusted memory device and to a trusted memory device. The shadowing is performed by concurrently writing data to both the trusted and untrusted memory devices, and concurrently reading data from both the trusted and the untrusted memory devices. All data returned from the trusted and untrusted memory devices in response to the read operations are compared, and if any data compared does not have a same value, a value from the trusted memory device is returned and an error indication is generated.

Abstract: Inconsistencies between cache and memory in a memory system operating in a computer are traced and corrected. A cache entry is checked against a counterpart memory entry to trace inconsistencies between the cache entry and the memory entry and to correct the cache entry. A page table entry in memory with a zero mapping mark is checked against a counterpart page entry in a translation lookaside buffer. Inconsistencies between the page table entry with a zero mapping mark and the existence of a counterpart page entry in the translation lookaside buffer is traced. The inconsistency is corrected by deleting the counterpart page entry in the translation lookaside buffer. Address mapping is checked comparing a page entry in the translation lookaside buffer against a counterpart page table entry in the memory. Inconsistencies between the page entry and the page table entry are traced and corrected.

Abstract: A single transaction technique for a journaling file system of a computer operating system in which a single file system transaction is opened for accumulating a plurality of current synchronous file system operations. The plurality of current synchronous file system operations are then performed and the single file system transaction closed upon completion of the last of the file system operations. The single file system operation is then committed to a computer mass storage device in a single write operation without the necessity of committing each of the separate synchronous file system operations with individual writes to the storage device thereby significantly increasing overall sytem performance. The technique disclosed is of especial utility in conjunction with UNIX System V based or other journaling operating systems.

Abstract: A system, method and computer program product of especial utility in allowing a user to insert a diagnostic computer program probe into an operating application computer program to either obtain a readout concerning the state of the application program or to introduce new behavior into it such that the results can be monitored. Through the provision of a number of application computer program probe points and corresponding diagnostic computer program probes herein disclosed, the invention may be utilized in conjunction with an operational application program and the corresponding diagnostic program may be developed independently of the application program the behavior of which is to be diagnosed.

Abstract: A transaction device driver that exports a transaction interface tailored to the requirements of conventional journaling file systems. The operating system file system informs the transaction device driver when a file system operation begins and ends and also informs the transaction driver about important data updates which have occurred since the beginning of the file system operation. The transaction device driver logs the updates as the data appears through the normal read/write/strategy entry points into the driver and, should the system fail while there are outstanding operations, ensures that either all of the changes for the operation will appear in the file system or that none of the changes will appear.

Abstract: Various versions of a computer file are provided without requiring copying the file or logging changed data, so that the files have consistent user data. A program module responds to a system call argument and allocates another node in file system tables and copies metadata information from the old node into the new node, so that both nodes contain the same data block allocation information. Portions of the module set shadow pointers in the old node to point to the new node, and in the new node to point to the old node. Changes to data are made with respect to the new node and fresh physical data blocks are allocated for the changed blocks. A method includes the steps of allocating a new node for storing file allocation information for another version of an existing file; logically connecting the new node to the existing node for file name and other purposes; and replacing node identification information in the directory with the new mode identification.

Abstract: In the tagged, hashed file system, each finite portion of a file of the user's data is tagged with a pathname (filename and path) and a logical offset of the data within the file. A hint, as to where the portion is located in storage in the THFS, is computed by hashing the pathname and the logical offset. Once the hint is provided, then the THFS commences to search storage from the location suggested by the hint until it finds a match between the tag on the portion with the pathname and logical offset. When a portion is to be written, the intended location for placement of the portion must be read to ensure that it is available for writing, i.e. empty. If the location is not available, then a search must be made for the closest available (empty) location, and the user data is written there. If during a read operation a matched tag is not found until an empty area is read, the search will terminate, and the user application will be notified that no file was found.

Abstract: A computer memory system and method utilizes a disk drive as a caching device to overcome the size and cost limitations of conventional semiconductor cache memory. Despite providing somewhat slower access times than semiconductor cache memory, utilizing one or more disk drives as a caching device allows enhanced performance to be maintained for longer times under sustained loads by effectively decreasing the latency of the primary storage device, combining relatively small random requests into larger sequential requests, balancing the input/output ("I/O") load over several disk devices and/or canceling duplicate writes.

Abstract: Software systems such as file systems in a computer are tested by scatter load testing. Scatter load testing is accomplished by the computer system applying randomly selected operative test situations to the software system. The operative test situations are randomized by the computer randomly selecting a geometry, or configuration, for the software system under test and randomly selecting a workload on the selected software system configuration. The randomization of workload selection can be further enhanced by expanding the workload to one or more tasks and randomly selecting objects, actions and parameters that make up each workload task to be performed during the test. As the random operative situation is run on the system, operation test results are output from the computer to indicate the performance of the software system being tested. Choice constraints may be placed on the random selection of the various test elements of the operative test situation.