Abstract: Systems, methods, apparatus and software can make use of separated I/O processors and strategy processors (implemented in hardware and/or software) to perform virtual device I/O operations. I/O processors operating on cluster nodes, storage appliance ports, or other devices can receive I/O operation requests directed to virtual devices, e.g., volumes or virtual logical units. Information about the request is forwarded to a strategy processor, operating independently or as part of larger volume management software where corresponding physical device I/O operations are determined. The physical device I/O operations can include additional information about the operations, e.g., tag information and summary information, for use in processing the virtual device I/O request. The physical device I/O operations are sent back to the I/O processor which executes the operations and/or passes the operation on to the appropriate storage device.

Abstract: A system and method for adaptively responding to update messages for a replica of a data object. A node may maintain first information regarding a replica of a data object. In various embodiments, the first information may comprise any kind of information regarding the replica of the data object. In one embodiment, the first information may comprise information indicative of accesses to the replica of the data object, e.g., may comprise access history information. In response to receiving a message for updating the replica of the data object, the node may respond to the message based on the first information. For example, the node may select one or more operations to perform based on the first information and may perform the one or more selected operations.

Abstract: A plurality of virtual circuits, each including at least two network nodes, may be established over a single network connection for inter-process messaging. The network connection may be opened asynchronously via a non-blocking open. A virtual circuit including three or more nodes may be implemented in a star formation or a relay formation. Messages may be sent as unicast or broadcast messages. An additional virtual circuit may be opened for the purpose of transmitting status information regarding the network connection between the networked computer systems.

Abstract: Procedures and systems for avoiding undesired trespass may be deployed in host processors that use storage arrays with automated fail-back and fail-over functions. In one embodiment, a method may synchronize path records in a storage array with path records in a host processor. The method may detect a failure of a first data path through a first controller on the storage array to a logical unit (LUN) on the storage array. In response to the failure, the host processor may initiate a failover on the storage array of the LUN, so that the LUN is accessed through a backup controller on the storage array. The host processor may also issue commands to pin the failed-over LUN to the backup controller. For example, the host processor may issue commands to set the default owner of the LUN to be the backup controller.

Abstract: In a data storage system, a storage management device includes at least a target mode driver, a data classifier in communication with the target mode driver, a plurality of storage buffers in communication with the target mode driver, a plurality of I/O managers in communication with the data classifier, and a physical store interface in communication with the plurality of I/O managers and with the plurality of storage buffers.

Abstract: A system and method for creating and utilizing dynamic directories in a computing system. A computing system includes a file system and a dynamic directory mechanism. The dynamic directory mechanism is configured to enable a user to create dynamic directories which are identifiable as having special behaviors associated with them. The user may create executable instructions for performing the special behaviors in a user space of an operating system and associate the special behaviors with selected native file system operations which may be performed on the directory. In response to detecting an operation on a directory is initiated, the mechanism determines whether the directory is a dynamic directory. If the directory is a dynamic directory, the mechanism determines whether any predetermined special behaviors have been defined for the initiated operation and if so performs the special behaviors.

Abstract: Various embodiments of systems and methods are disclosed for using priority information when handling error conditions for a storage resource. In some embodiments, a method involves detecting an error condition, which is associated with a storage resource, and selecting an error-correcting action in response to detection of the error condition. Selection of the error-correcting action is based on priority information. The priority information identifies respective priorities of several applications. At least one of the applications uses the storage resource when accessing application data.

Abstract: A method for identifying a time at which first data was written to a data store. A data store is configured to respond to data requests made to the data store with the data in the data store at a first time in the past. The method can be used to identify a time, for example, at which a data store was corrupted.

Abstract: A system and method for managing the environment of software processes in a computer system. A computer system comprises a processor and at least one process environment comprising one or more environment variables. The processor executes one or more processes, intercepts the launch of a process, sets at least one environment variable to a first value, and continues the launch of the process. Setting the environment variable may enable a profiler process. The processor may set at least one environment variable for the process to a value which is chosen irrespective of a value of the environment variable of a parent process of the process. Further, the processor may set at least one environment variable for the process to a default value if a data repository does not contain an entry that has an identification which corresponds to the process.

Abstract: Systems and methods for I/O fencing in a shared storage environment are provided. Prior to initiating an I/O request, when feasible, the current time from a local timer is compared to the current state of an interval obtained for the target device. As a result, a device reset occurring while the interval is viable does not arbitrarily end a multiphase I/O operation. However, a device reset occurring once the lease has expired results in a delay or termination of the multiphase I/O operation. As a result, multiphase I/O operations from initiating hosts that have lost contact with the shared storage environment are not allowed to corrupt the shared storage devices.

Abstract: A method, system and computer accessible medium for expiring access tokens in preparation for freezing file images. A metadata server may maintain a next scheduled quiesce time and may issue access tokens configured to expire before the next scheduled quiesce time. A metadata server may set an access token's expiration time to a maximum expiration time indicated by the next scheduled quiesce time or may set an access token's expiration time to a default expiration time if the default expiration time is earlier than the maximum expiration time. A storage device may recognize and enforce the access token's expiration time.

Abstract: A method, system, computer system, and computer-readable medium to perform root cause analysis of failure of an application program in a clustering environment. Upon the occurrence of a problem or event of interest, cluster configuration data can be obtained to provide a common context for events occurring at different software layers supporting an application. Diagnostic information produced by the different software layers can be obtained from various log files, which are typically in different formats and on different nodes in the cluster. The diagnostic information can be viewed in the context of the cluster and filtered to identify events related to the failure. The related events can be presented in a time-ordered sequence to assist in analysis of the event of interest. Patterns of events that led to the failure can be identified and documented for use in further problem analysis and for taking preventative and/or corrective measures.

Abstract: An apparatus or method for preserving the relationships or dependencies between content of files in a file system or between content of files in separate file systems. The preservation of relationships or dependencies may require the preservation of the files and their content as well. In one embodiment, the method includes receiving a first instruction that, when implemented, performs an operation involving a first file in a file system, wherein the first file is related to the second file. In response to receiving the first instruction, a second instruction is selected that, when implemented, performs a second operation involving the first file or a second file, wherein the second instruction is implemented before or after implementing the first instruction.

Abstract: Methods, systems, and apparatus can provide individual users of a computer system a means to share their quotas to resources accessible through that system. In one embodiment, this is accomplished, in part, by providing a shared quota descriptor understood by a file system and that can be manipulated by individual users. To that end, the present invention further provides individual users access to mechanisms by which to create and adjust shared quotas.

Abstract: Systems and methods for performing sparse backups are disclosed. One method may involve: receiving information indicating unallocated extents from a file system that organizes data on a primary storage device; copying to a backup storage device data from extents of the primary storage device, where the unallocated extents indicated by the information are not copied; and for each of a plurality of copied extents, storing a mapping from an original extent on the primary storage device to a new extent on the backup storage device into which data stored in that original extent is copied. A backup volume that includes the data included in plurality of copied extents may be mounted, and the mapping may be used to translate accesses to the extents on the backup volume to extents on the backup storage device.

Abstract: A cluster comprises a plurality of computer systems, wherein each of the plurality of computer systems is configured to execute one or more virtual machines. Each of the plurality of computer systems comprises hardware and a plurality of instructions. The plurality of instructions, when executed on the hardware, migrates at least a first virtual machine executing on a first computer system of the plurality of computer systems to a second computer system of the plurality of computer systems. The plurality of instructions migrates the first virtual machine responsive to a first load of the first computer system prior to the migration exceeding a second load of the second computer system prior to the migration.

Abstract: A method, computer program product and system that enables dynamic determination of device attributes and dynamic configuration of device drivers for storage devices in a heterogeneous storage environment. Attributes of a device are dynamically determined by an application program, and those attributes are used by the application program to configure the device driver. The application program and the storage device being configured remain operational during the reconfiguration process.

Abstract: Network fabric events may be utilized to proactively handle network path outages. A storage network virtualization manager may receive a network fabric event indicating a failure along a network path to a storage device and in response may initiate a proactive error handling mechanism. A storage network virtualization manager may proactively handle a network path failure before I/O requests via that network path fail. The proactive error handling mechanism may be initiated and completed prior to or without a host receiving an indication that an access request to a storage device on the network path has failed. Proactive error handling in response to network fabric events may reduce the number of I/O failures and retries and may also reduce the length of time access requests to storage devices affected by a network fabric path failure must be quiesced.

Abstract: An interactive system for debugging programs in which a persistent data base system responds to update queries containing debugging information from a debugging information source and to read queries on the debugging information from an interactive interface. The interactive interface produces the read queries in response to inputs from users and formats the results of the read queries as required by the user. One source of inputs is a standard Web browser for which the interactive interface functions as a Web server. The system also includes a command channel by which the source of debugging information receives commands from the interactive interface. In one embodiment, the command channel is implemented in the data base. In a disclosed implementation, the source of debugging information provides memory debugging information. Also disclosed are techniques for using an automatic memory management system to reduce memory fragmentation and heap footprint size.

Abstract: One method of updating a change track map involves resetting a mirror recovery map for a data volume. Just before the mirror recovery map is reset, a change track map for the data volume can be updated, using the mirror recovery map. The mirror recovery map can be reset by a data element of a data processing system, while the change track map can be updated by a control element of the data processing system.