Abstract: A leak detector (190) includes a sensor head (260), a light source (200) optically coupled to the sensor head and operable to generate excitation light. A detector (205) is optically coupled to the sensor head and operable to detect fluorescence light. A signal processing unit (210) is coupled to the detector and operable to signal a leak condition responsive to an intensity of the fluorescence light exceeding a threshold. A fluid-tight enclosure (235) encloses at least the light source, the detector, and the signal processing unit.

Abstract: Example apparatus, methods, and computers facilitate improving spatial locality of file system block allocations for related items. One example method includes accessing a block allocation request that is configured to control a computer to allocate a block of storage available on a storage device and, upon determining that the block allocation request includes a session key that identifies a session associated with a block reservation pool, controlling the computer to allocate a block of storage from the block reservation pool to satisfy the block allocation request rather than allocating a block of storage from generally available blocks of storage. The block reservation pool includes blocks of storage on the storage device that satisfy a spatial locality relationship determined by a pre-read technique associated with the storage device.

Abstract: Example apparatus, methods, and computers facilitate improving spatial locality of file system block allocations for related items. One example method includes accessing a block allocation request that is configured to control a computer to allocate a block of storage available on a storage device and, upon determining that the block allocation request includes a session key that identifies a session associated with a block reservation pool, controlling the computer to allocate a block of storage from the block reservation pool to satisfy the block allocation request rather than allocating a block of storage from generally available blocks of storage. The block reservation pool includes blocks of storage on the storage device that satisfy a spatial locality relationship determined by a pre-read technique associated with the storage device.

Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. Version information about subsystems is acquired by a leader node when forming a cluster membership and distributed to all nodes in the cluster to enable proper messaging during operation. Access to files on the storage devices is arbitrated by the cluster filesystem using tokens. Upon detection of a change in location of the metadata server, client nodes waiting for a token are interrupted to check on the status of at least one of data and node availability. The cluster operating system maintains consistency of a mirrored data volume by automatically ensuring replication of a mirror leg while continuing to accept access requests to the mirrored data volume.

Abstract: A computer system with read/write access to storage devices creates a snapshot of a data volume at a point in time while continuing to accept access requests to the mirrored data volume by copying before making changes to the base data volume. Multiple snapshots may be made of the same data volume at different points in time. Only data that is not stored in a previous snapshot volume or in the base data volume are stored in the most recent snapshot volume.

Abstract: A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. Version information about subsystems is acquired by a leader node when forming a cluster membership and distributed to all nodes in the cluster to enable proper messaging during operation. Access to files on the storage devices is arbitrated by the cluster filesystem using tokens. Upon detection of a change in location of the metadata server, client nodes waiting for a token are interrupted to check on the status of at least one of data and node availability. The cluster operating system maintains consistency of a mirrored data volume by automatically ensuring replication of a mirror leg while continuing to accept access requests to the mirrored data volume.