Abstract: Methods, systems, and computer program products for managing quality of service for shared storage accessed by a plurality of nodes are disclosed. According to one method, at a node of a plurality of nodes sharing access to a first disk array, quality-of-service (QoS) metadata associated with a portion of the disk array are requested from a server, wherein the QoS metadata includes at least one performance criterion for the portion of the disk array. I/O performance is monitored for the portion of the disk array in response to receiving the QoS metadata. The monitored I/O performance is compared with the QoS metadata. Based upon the comparison of the monitored I/O performance with the QoS metadata, it is determined whether a QoS violation has occurred. In response to determining that a QoS violation has occurred, the server is requested to migrate data associated with the portion of the disk array.

Abstract: An improved policy enforcement architecture includes several components that improve the performance of policy enforcement in a hierarchical storage environment. A File System Query instruction permits a richer set of queries to be expressed by a policy engine, thereby permitting more complex policies to be implemented with ease. The File System result is generated at the file server, and only files of interest are forwarded to the policy engine. The file system query advantageously may be applied against a pre-generated index having one more characterizing attributes to further reduce the processing required to retrieve policy data. An Index Build instruction, added to a programming interface, allows a policy engine generate the characterizing indices in advance of use. Index maintenance techniques maintain consistency between the index and the file system to ensure that the policy can be enforced using accurate file information.

Abstract: A hierarchical storage system is constructed from file servers and a policy engine server by building upon a file migration service. Offline attributes are added to file system inodes in a primary file server, file system parameters are added in the primary server, an offline read access method field is added to a connection database, and the primary file server is programmed to use these attributes and parameters for selecting a particular method (such as a partial read migration or a pass through read method) for read access to an offline file. In this fashion, the primary file server is provided with flexibility for selecting a particular one of a number of migration methods depending on various conditions, in order to improve the trade-off between the cost of storage and delay in file access.

Abstract: An improved policy enforcement architecture includes several components that improve the performance of policy enforcement in a hierarchical storage environment. A File System Query instruction permits a richer set of queries to be expressed by a policy engine, thereby permitting more complex policies to be implemented with ease. The File System result is generated at the file server, and only files of interest are forwarded to the policy engine. The file system query advantageously may be applied against a pre-generated index having one more characterizing attributes to further reduce the processing required to retrieve policy data. An Index Build instruction, added to a programming interface, allows a policy engine generate the characterizing indices in advance of use. Index maintenance techniques maintain consistency between the index and the file system to ensure that the policy can be enforced using accurate file information.

Abstract: An improved policy enforcement architecture includes several components that improve the performance of policy enforcement in a hierarchical storage environment. A File System Query instruction permits a richer set of queries to be expressed by a policy engine, thereby permitting more complex policies to be implemented with ease. The File System result is generated at the file server, and only files of interest are forwarded to the policy engine. The file system query advantageously may be applied against a pre-generated index having one more characterizing attributes to further reduce the processing required to retrieve policy data. An Index Build instruction, added to a programming interface, allows a policy engine generate the characterizing indices in advance of use. Index maintenance techniques maintain consistency between the index and the file system to ensure that the policy can be enforced using accurate file information.

Abstract: Methods, systems, and computer program products for providing access to shared storage by a plurality of nodes are disclosed. According to one method, at a node of a plurality of nodes sharing access to a disk array, an application input/output (I/O) operation and whether sufficient space in the disk array has been mapped at the node for the I/O operation are detected. In response to detecting that sufficient space in the disk array has not been mapped at the node for the I/O operation, a map for the I/O operation including physical disk access information is requested and obtained from a server. The physical disk access information included within the map for the application I/O operation obtained from the server is used to perform the I/O operation by accessing the disk array without intervention by the server.

Abstract: A shared-disk cluster system includes a cluster membership manager framework which coordinates the joining or leaving among all nodes in a cluster including taking the multiple layers of involved subsystems through transitions. Subsystems are notified of transitions in particular order depending upon the transition, and all nodes' subsystems receiving a notification must process that notification prior to another layer of subsystems being notified. One of the subsystems registered for notification is an event manager in user space. The event manager carries out transfers of client services, including user applications, resulting from nodes joining and leaving the cluster. This includes a registration and launch service which registers a node, or multiple nodes, in a cluster which claims, or is assigned, responsibility for the service and provides an optional launching function which initiates the client service upon successful registration.