Abstract: A mechanism is provided that aggregates data in a way that permits data to be deleted efficiently, while minimizing the overhead necessary to support bulk deletion of data. A request is received for automatic deletion of segments in a container and a waterline is determined for the container. A determination is made if at least one segment in the container falls below the waterline. Finally, in response to one segment falling below the waterline, the segment from the container is deleted. Each object has an associated creation time, initial retention value, and retention decay curve (also known as a retention curve). At any point, based on these values and the current time, the object's current retention value may be computed. The container system continually maintains a time-varying waterline: at any point, objects with a retention value below the waterline may be deleted.

Abstract: A data storage system and method for providing consistent data to multiple clients based on data modification information as existing data is updated and new data is written to the system. The information indicates the modification status of each data block and identifies which data blocks have been modified during a certain time interval. The clients may query and update the modification information by submitting requests through a request processor. The data modification information includes an Altered Block Map that indicates block modification status and a Toggle Block Map that identifies which blocks have been modified. The system further includes a Modification Counter a Pending Reset Counter for improved recognition and handling of the modified data.

Abstract: A method and system for managing workloads in an autonomic computer system based on feedback and feed-forward performance information. The method establishes a performance objective for the system, determines a measure of instantaneous demand in the system, continuously tracks the objective with respect to the measure, forecast a future demand based on an autoregressive time series of the system, and adjusts the control parameters of the system to meet the objective. The performance objective is associated with a confidence level and typically includes a desired system response time. The tracking step includes obtaining performance data on the system and storing the performance data in a persistent data store. The demand forecasting uses a Spectral Forecasting procedure to forecast a future workload from a present workload.

Abstract: A data storage system and method for providing consistent data to multiple clients based on data modification information as existing data is updated and new data is written to the system. The information indicates the modification status of each data block and identifies which data blocks have been modified during a certain time interval. The clients may query and update the modification information by submitting requests through a request processor. The data modification information includes an Altered Block Map that indicates block modification status and a Toggle Block Map that identifies which blocks have been modified. The system further includes a Modification Counter a Pending Reset Counter for improved recognition and handling of the modified data.

Abstract: A system for ensuring high reliability in a block service disk array system while promoting high performance by logically writing all changes to strides on the array while physically writing ahead to a log only a subset of the changes. Specifically, for changes of only a strip or so, the changes are written to a log, along with a commit record, and then written to disk, later deleting the changes from the log. In contrast, for relatively larger changes, i.e., for an entire (or nearly entire) stride, the old stride is not overwritten by the new, but rather is written to a new location on the disk, with the new and old locations and a commit record (but not the new stride itself) being logged and with the entries for the locations in the stride mapping table swapped with each other. In an alternate embodiment, blocks can be written to temporary locations in a RAID-1 area and lazily moved to home locations in a RAID-5 area of an array of disks.

Abstract: A decentralized file system based on a network of remotely encrypted storage devices is disclosed. The file system includes a network to which a network client, a secure remotely encrypted storage device, a key manager, and a lock manager are attached. The system organizes data as files and directories. Files or directories are composed of one or more streams, which logically partition the data associated with the files or directories. The device serves as a repository of the system's data. The key manager controls data access keys while the lock manager handles consistency of the files. A network user may have read or write access to a file. Access is controlled using keys and access lists maintained by the key manager.

Abstract: A network storage device is disclosed for use in a secure array of such devices to support a distributed file system. Each device is an independent repository of remotely encrypted data objects to be accessed by authorized network clients. All encryption is done by the clients, rather than by the devices. In order for the system to revoke access to an object on the device, the object must be re-encrypted. Each storage device has a device owner for controlling access to the device's data. All data requests from the clients and responses to them are authenticated using keys derived from the owner key and hashed message authentication codes.