Abstract: A storage system uses a block-level file system to manage physical storage of data blocks of logical units, the file system being mounted on an owning one of a set of storage processors. The storage processors redirect received storage requests to the owning storage processor, and periodically the amount of redirection is evaluated. If the amount of redirection is higher than a threshold, then the file system is dismounted at the owning storage processor and mounted at another storage processor to reduce the amount of redirection.

Abstract: In a data storage system, a fixture communication channel is created for communications between a fixture and another component, where the fixture is a component of a device driver that provides extended input/output functionality with respect to one or more storage devices. A handle identifies the fixture communication channel, and callbacks are registered with a driver handler and reference callback functions of the fixture. Fixture communication messages each include the handle and a message-specific operation code for an operation to be performed by the fixture, and each is conveyed by (1) issuing a fixture-control input/output control command to the handler that includes the handle and message-specific operation code, and (2) at the handler, using the handle and message-specific operation code to select a callback and invoke a corresponding callback function of the fixture.

Abstract: A method of creating point-in-time views of data on a disk involves initiating from a host at least one session of writing data to a disk. For each session, an entry is created and stored on an array on the disk. The sessions are assigned unique IDs to each, and provide indications where data for a particular session may be found on the disk.

Abstract: A method and system for synchronizing a plurality of data images in a computer system, includes a primary image and at least one secondary image which are synchronized. A host computer issues write requests to a primary image site which is also transmitted to a secondary image site. Writing to the primary image and the secondary image at the primary image site and secondary site is conducted simultaneously. If a failure to write to the secondary image occurs, a fracture log is created which is a bitmap representative of changed regions in the primary image at the primary image site in response to the write request. When writing to the secondary image is restored, the log can be used to synchronize the primary image and the secondary image.