Systems and methods, including computer program products, providing high-availability in server systems. In one implementation, a server system is cluster of two or more autonomous server nodes, each running one or more virtual servers. When a node fails, its virtual servers are migrated to one or more other nodes. Connectivity between nodes and clients is based on virtual IP addresses, where each virtual server has one or more virtual IP addresses. Virtual servers can be assigned failover priorities, and, in failover, higher priority virtual servers can be migrated before lower priority ones. Load balancing can be provided by distributing virtual servers from a failed node to multiple different nodes. When a port within a node fails, the node can reassign virtual IP addresses from the failed port to other ports on the node until no good ports remain and only then migrate virtual servers to another node or nodes.

High-availability cluster virtual server system

A system and method for dynamic data recovery is described. The system and method for dynamic data recovery operates on a computer storage system that includes a plurality of disk drives for storing parity groups. Each parity group includes storage blocks. Each of the storage blocks is stored on a separate disk drive such that no two storage blocks from a given parity set reside on the same disk drive. The computer storage system further includes a recovery module to dynamically recover data that is lost when at least a portion of one disk drive in the plurality of disk drives becomes unavailable. The recovery module is configured to produce a reconstructed block by using information in the remaining storage blocks of a parity set that corresponds to an unavailable storage block. The recovery module is further configured to split the parity group corresponding to an unavailable storage block into two parity groups if the parity group corresponding to the unavailable storage block spanned all of the drives in the plurality of disk drives.

Dynamic data recovery

An intelligent network interface card (INIC) or communication processing device (CPD) works with a host computer for data communication. The device provides a fast-path that avoids protocol processing for most messages, greatly accelerating data transfer and offloading time-intensive processing tasks from the host CPU. The host retains a fallback processing capability for messages that do not fit fast-path criteria, with the device providing assistance such as validation even for slow-path messages, and messages being selected for either fast-path or slow-path processing. A context for a connection is defined that allows the device to move data, free of headers, directly to or from a destination or source in the host. The context can be passed back to the host for message processing by the host. The device contains specialized hardware circuits that are much faster at their specific tasks than a general purpose CPU. A preferred embodiment includes a trio of pipelined processors devoted to transmit, receive and utility processing, providing full duplex communication for four Fast Ethernet nodes.

TCP/IP offload network interface device

A system for protocol processing in a computer network has an intelligent network interface card (INIC) or communication processing device (CPD) associated with a host computer. The INIC provides a fast-path that avoids protocol processing for most large multi-packet messages, greatly accelerating data communication. The INIC also assists the host for those message packets that are chosen for processing by host software layers. A communication control block for a message is defined that allows DMA controllers of the INIC to move data, free of headers, directly to or from a destination or source in the host. The context is stored in the INIC as a communication control block (CCB) that can be passed back to the host for message processing by the host. The INIC contains specialized hardware circuits that are much faster at their specific tasks than a general purpose CPU. A preferred embodiment includes a trio of pipelined processors with separate processors devoted to transmit, receive and management processing, with full duplex communication for four fast Ethernet nodes.

Fast-path apparatus for receiving data corresponding to a TCP connection

A system and method for remote asynchronous replication or mirroring of changes in a source file system snapshot in a destination replica file system using a scan (via a scanner) of the blocks that make up two versions of a snapshot of the source file system, which identifies changed blocks in the respective snapshot files based upon differences in volume block numbers identified in a scan of the logical file block index of each snapshot. Trees of blocks associated with the files are traversed, bypassing unchanged pointers between versions and walking down to identify the changes in the hierarchy of the tree. These changes are transmitted to the destination mirror or replicated snapshot. This technique allows regular files, directories, inodes and any other hierarchical structure to be efficiently scanned to determine differences between versions thereof. The changes in the files and directories are transmitted over the network for update of the replicated destination snapshot in an asynchronous (lazy write) manner. The changes are described in an extensible, system-independent data stream format layered under a network transport protocol. At the destination, source changes are used to update the destination snapshot. Any deleted or modified inodes already on the destination are moved to a temporary or “purgatory” directory and, if reused, are relinked to the rebuilt replicated snapshot directory. The source file system snapshots can be representative of a volume sub-organization, such as a qtree.

System and method for determining changes in two snapshots and for transmitting changes to destination snapshot

A computer system employing a multiple facility operating system architecture is disclosed. The computer system includes a plurality of processor units (12, 14, 16) for implementing a predetermined set of peer-level facilities (162, 164, 166, 168) wherein each peer-level facility includes a plurality of related functions and a communications bus (22) interconnecting the processor units. Each of the processor units includes a central processor (30, 80, 100) and the stored program (68, 86, 134) that, upon execution, provides for the implementation of a predetermined peer-level facility and for performing a multi-tasking interface function. The multi-tasking interface function is responsive to control messages for selecting for execution functions of the predetermined peer-level facility and is responsive to the predetermined peer-level facility for providing control messages to request or to respond to the performance of functions of another peer-level facility of the computer system. The multi-tasking interface functions of the processor units communicate among one another via the communication bus.

Multiple facility operating system architecture

This is achieved in a computer system employing a multiple facility operating system architecture. The computer system includes a plurality of processor units for implementing a predetermined set of peer-level facilities wherein each peer-level facility includes a plurality of related functions and a communications bus for interconnecting the processor units. Each of the processor units includes a central processor and the stored program that, upon execution, provides for the implementation of a predetermined peer-level facility of the predetermined set of peer-level facilities, and for performing a multi-tasking interface function. The multi-tasking interface function is responsive to control messages for selecting for execution functions of the predetermined peer-level facility and that is responsive to the predetermined peer-level facility for providing control messages to request or to respond to the performance of functions of another peer-level facility of the computer system. The multi-tasking interface functions of each of the plurality of processor units communicate among one another via the network bus.

Multiple software-facility component operating system for co-operative processor control within a multiprocessor computer system



We aimed to compare the diagnostic performance of an objective set of magnetic resonance imaging (MRI) criteria named the cleft sign with traditional reads for pre-operative diagnosis of peroneal tendon tears. We also investigated the relationship between peroneus brevis tendon tears and muscle quality.



Two blinded readers retrospectively and independently evaluated pre-operative ankle MRI studies of 38 patients who had undergone peroneal tendon surgery for peroneal tendon tears, peroneus brevis muscle quality, and the cleft sign. MRI examinations from 38 control subjects were also reviewed for peroneus brevis muscle quality. The diagnostic performances of MRI for peroneal tendon tears with and without application of the cleft sign were analyzed. The correlation between peroneus brevis fatty atrophy and tendon tears was also examined.



In patients without prior peroneal surgery, the sensitivity and specificity of MRI for peroneus brevis tendon tears were 60%/89% and 80%/78% for readers 1 and 2, respectively. Application of the cleft sign significantly increased sensitivity in reader 1 to 95%, with a non-significant increase in accuracy in both readers. The interobserver reliability for the cleft sign was moderate for peroneus brevis (κ = 0.57). No significant difference in peroneus brevis muscle quality was present between subjects with and without peroneus brevis tendon tears and between surgical and control patients.



In patients without prior peroneal tendon surgery, the cleft sign can significantly improve reader diagnostic sensitivity for peroneus brevis tears. The muscle quality of the peroneus brevis has limited value in MRI diagnosis of peroneal tendon tears.


Improving pre-operative MRI diagnosis of peroneal tendon tears with a new objective sign and assessing the value of peroneus brevis fatty atrophy

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Multiple facility operating system architecture

Multiple software-facility component operating system for co-operative processor control within a multiprocessor computer system

Improving pre-operative MRI diagnosis of peroneal tendon tears with a new objective sign and assessing the value of peroneus brevis fatty atrophy