Showing papers by "Frank B. Schmuck published in 2000"

Dynamically switching between different types of concurrency control techniques to provide an adaptive access strategy for a parallel file system

Abstract: Concurrent access to data is managed through concurrency control techniques. Various types of techniques are employed to manage the access, including locking-based techniques and non-locking-based techniques. A dynamic switch from one type of concurrency control technique (e.g., a locking-based technique) to a different type of concurrency control technique (e.g., a non-locking-based technique) is enabled. This switching is based on access patterns and/or application requirements for each file. The switching allows enhanced performance for both coarse-grain sharing and fine-grain sharing of data.

System for determining the order and frequency in which space is allocated on individual storage devices

Abstract: Space is allocated on data storage devices in proportion to weights associated with the storage devices. The weights can be dynamically adjusted at any time in order to accommodate changes in the system and to better utilize the storage devices. The technique used to perform the allocating is independent of the weights used by the allocating. Further, the allocation technique can accommodate general purpose data streams having varying lengths and/or varying access patterns, as well as special purpose data streams, such as video streams.

Plurality of file systems using weighted allocation to allocate space on one or more storage devices

Abstract: Space is allocated on storage devices in proportion to weights associated with the storage devices. The space is allocated by a plurality of file systems. In particular, space may be allocated on any one of the devices by one or more of the file systems. The weights can be dynamically adjusted at any time in order to accommodate changes in the system and to better utilize the storage devices. However, since more than one file system may be allocating space on one or more of the storage devices, changes in the weights are propagated to the various file systems that may utilize the information.

Non-disruptive migration of coordinator services in a distributed computer system

Abstract: This invention allows a related set of coordinator services to migrate from one node to another without disrupting applications on any of the nodes in the system. Unlike other methods, this invention allows a set of interdependent services to be brought to “quiescence” and migrated together. Since service operations depend upon the results and/or data of other service operations, any particular operation can only complete properly when those other operations return data necessary for the completion of the dependent operation. Therefore, this invention permits the completion of non-disruptive migration by phasing the “quiescence” of the services. Operations that are most dependent upon other operations are suspended before those other operations; then the process waits for any current operations to complete. Once the first phase of dependent operations have completed, the next phase of dependent operational services are suspended, the process waits for completion of those operations and so on until there are no more phases to the “quiescence” process. Hence, the invention is applicable to more complex distributed applications than previous methods.

Maintenance of free resource information in a distributed system

Abstract: A method for managing a shared resource that is allocated among nodes in a distributed computing system includes receiving periodic reports from the nodes regarding their respective allocations of the resource. Responsive to the periodic reports, an approximate amount of the resource that is free for further allocation is determined. Typically, the shared resource is a data storage resource, such as a plurality of disks linked to the nodes by a network, which disks are commonly accessible to multiple ones of the nodes.