Ncr Corporation

Steven R McDowell

Vernon Keith Boland

Ernest C Coskrey, Iv

Harold B Raynor

Methods for optimizing disk mirroring synchronization and write operations. Disk mirror synchronization, wherein date stored on a first storage device is duplicated on a second storage device, is performed by examining each data block contained within the first storage device and identifying data blocks that contain only zero data and data blocks containing non-zero data. Requests are sent to the second storage device to create a zeroed data block corresponding to each data block on the first disk device that contains only zero data. A copy of each data block on the first disk drive that contains non-zero data is written to the second storage device. Disk mirror write operations, wherein data written to the first storage device is duplicated on the second storage device, are optimized by intercepting write requests directed to the first storage device, and examining each data block within the write requests to determine if the data block contains only zero data. If a data block contains only zero data, a request is sent to the second storage device to create a zeroed block. If a data block contains non-zero data, the data block is transmitted to the second storage device.

Zeroed block optimization in disk mirroring applications

A computer system operable to provide nodes of a cluster with a quorum resource includes a network interface controller, a mass storage device, a processor, and memory. The network interface controller is operable to send messages to the nodes via a network and receive messages from the nodes via the network. The mass storage device includes storage that is used to implement the quorum resource and that is accessible by the nodes via the network interface controller. The processor is operably coupled to the network interface controller and the mass storage device. The memory is operably coupled to the processor and includes instructions, which when executed by the processor, cause the processor to process a first message requesting ownership of the quorum resource that is received from a first node of the cluster via the network interface controller. Furthermore, the instructions cause the processor to determine whether the first node already owns the quorum resource in response to receiving the first message. Moreover, the instructions cause the processor to determine whether a second message requesting ownership of the quorum resource is received from a second node of the cluster within a predetermined time period of receiving the first message it the first node does not already own the quorum resource. The instructions cause the processor to grant ownership of the quorum resource to the first node if the second message is not received within the predetermined time period.

Quorum arbitrator for a high availability system

A system for mirroring data and disk drive device state over a network between a source computer including a first non-shared disk drive storage device and a target computer including a second non-shared disk drive storage device. The system includes layered software drivers installed within the source computer above the device driver for the first disk drive storage device for capturing and examining write requests directed to the first disk drive storage device, and transmitting the write request and extracted device state information to the target computer. Software drivers installed within the target computer above the device driver for the second disk drive storage device direct the received write requests to the second disk drive storage device, and the received device state information to volatile storage within the target computer.

Virtualized storage devices for network disk mirroring applications

A computing apparatus that is capable of taking over processing from a primary computer. The computing apparatus includes a confirmation-based file system cache flush mechanism that prevents loss of uncommitted data during a primary computer failure and a filter driver that is capable of functioning as a network file system driver in a first mode of operation and as an invisible pass through to the underlying local file system driver in a second mode of operation. A computer system that includes a primary and a secondary computer that have these features is also disclosed.

File system filter driver apparatus and method

An asynchronous disk mirroring system for use within a network computer system. The disk mirroring system includes a first storage volume connected to receive write requests from the computer system; a write queue connected to also receive the write requests directed to the first storage volume; and a second storage volume connected to the write queue to receive the write requests. The write queue operates to delay the time of receipt of the write requests by the second storage volume. Write requests are passed through the write queue, comprising a plurality of serially connected write buffers, in a first-in, first-out (FIFO) order. A log file connected to receive the delayed write requests from the write queue is also included in the disk mirroring system to provide for log-based mirror reconstruction and check-pointing of the mirrored volumes.

Growing community of inventors

Lexington, SC, United States of America

Steven R McDowell