Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Various embodiments are provided for managing a global cache coherency in a distributed shared caching for a clustered file system (CFS). The CFS manages access permissions to an entire space of data segments by using the DSM module. In response to receiving a request to access one of the data segments, a calculation operation is performed for obtaining most recent contents of one of the data segments. The calculation operation performs one of providing the most recent contents via communication with a remote DSM module which obtains the one of the data segments from an associated external cache memory, instructing by the DSM module to read from storage the one of the data segments, and determining that any existing contents of the one of the data segments in the local external cache are the most recent contents.

Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Systems. Methods, and Computer Program Products are provided managing global cache coherency and reducing contention and messaging traffic in a distributed shared caching for a clustered file systems (CFS). The CFS manages access to data segment space of the data segments shared between a cluster of nodes by using the file access component. A CFS disk space is partitioned into regions and disk objects are partitioned into groups. Each of the regions and the groups are assigned to a CFS agent residing on each one of the cluster of nodes.

Abstract: Real-time reduction of CPU overhead for data compression is performed by a processor device in a computing environment. Non-compressing heuristics are applied on a randomly selected data sample from data sequences for determining whether to compress the data sequences. A compression potential is calculated based on the non-compressing heuristics. The compression potential is compared to a threshold value. The data sequences are either compressed if the compress threshold is matched, compressed using Huffman coding if Huffman coding threshold is matched, or stored without compression.

Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Systems. Methods, and Computer Program Products are provided for managing a global cache coherency in a distributed shared caching for a clustered file systems (CFS). The CFS manages access permissions to an entire space of data segments by using the DSM module. In response to receiving a request to access one of the data segments, a calculation operation is performed for obtaining most recent contents of one of the data segments. The calculation operation performs one of providing the most recent contents via communication with a remote DSM module which obtains the one of the data segments from an associated external cache memory, instructing by the DSM module to read from storage the one of the data segments, and determining that any existing contents of the one of the data segments in the local external cache are the most recent contents.

Abstract: Systems. Methods, and Computer Program Products are provided for managing a global cache coherency in a distributed shared caching for a clustered file systems (CFS). The CFS manages access permissions to an entire space of data segments by using the DSM module. In response to receiving a request to access one of the data segments, a calculation operation is performed for obtaining most recent contents of one of the data segments. The calculation operation performs one of providing the most recent contents via communication with a remote DSM module which obtains the one of the data segments from an associated external cache memory, instructing by the DSM module to read from storage the one of the data segments, and determining that any existing contents of the one of the data segments in the local external cache are the most recent contents.

Abstract: Systems. Methods, and Computer Program Products are provided for managing a global cache coherency in a distributed shared caching for a clustered file systems (CFS). The CFS manages access permissions to an entire space of data segments by using the DSM module. In response to receiving a request to access one of the data segments, a calculation operation is performed for obtaining most recent contents of one of the data segments. The calculation operation performs one of providing the most recent contents via communication with a remote DSM module which obtains the one of the data segments from an associated external cache memory, instructing by the DSM module to read from storage the one of the data segments, and determining that any existing contents of the one of the data segments in the local external cache are the most recent contents.

Abstract: Systems. Methods, and Computer Program Products are provided for managing a global cache coherency in a distributed shared caching for a clustered file systems (CFS). The CFS manages access permissions to an entire space of data segments by using the DSM module. In response to receiving a request to access one of the data segments, a calculation operation is performed for obtaining most recent contents of one of the data segments. The calculation operation performs one of providing the most recent contents via communication with a remote DSM module which obtains the one of the data segments from an associated external cache memory, instructing by the DSM module to read from storage the one of the data segments, and determining that any existing contents of the one of the data segments in the local external cache are the most recent contents.

Abstract: Systems. Methods, and Computer Program Products are provided managing a global cache coherency and reducing messaging traffic for coordination of access permissions in a distributed shared caching for a clustered file systems (CFS). The CFS manages access permissions to an entire space of the data segments by using the DSM module. In response to processing a request message from a remote DSM module to access one of the data segments, including in a response message permission to access the one of the data segments, and deciding if one of a transfer of ownership, and most recent contents of the one of the data segments should be included in the response message for the permission to access the one of the data segments. The last two components of the response message depend upon availability of the one of the data segments that is requested in a local external cache.

Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Systems and methods enabling search of a repository for the location of data that is similar to input data, using a defined measure of similarity, in a time that is independent of the size of the repository and linear in a size of the input data, and a space that is proportional to a small fraction of the size of the repository. Additionally, remote operations are accomplished with significantly reduced system bandwidth by implementing remote differencing operations.

Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Exemplary method, system, and computer program product embodiments for scalable data deduplication working with small data chunk in a computing environment are provided. In one embodiment, by way of example only, for each of the small data chunk, a signature is generated based on a combination of a representation of characters that appear in the small data chunk with a representation of frequencies of the small data chunk. A signature is generated based on a combination of a representation of characters that appear. The signature is used to help in selecting the data to be deduplicated. Additional system and computer program product embodiments are disclosed and provide related advantages.

Abstract: Exemplary method, system, and computer program product embodiments for scalable data deduplication working with small data chunk in a computing environment are provided. In one embodiment, by way of example only, for each of the small data chunk, a signature is generated based on a combination of a representation of characters that appear in the small data chunk with a representation of frequencies of the small data chunk. A signature is generated based on a combination of a representation of characters that appear. The signature is used to help in selecting the data to be deduplicated. Additional system and computer program product embodiments are disclosed and provide related advantages.

Abstract: Systems. Methods, and Computer Program Products are provided for recovering transactions of failed nodes using a recovery procedure in a clustered file system (CFS). A data segment is determined that the data segment should be copied to a final storage location by validating that an ownership of the data segment is not associated with any other operational node, via a distributed shared memory (DSM) agent. The ownership of the data segment is set to a local DSM agent.

Abstract: Systems and methods for implementing a distributed shared memory (DSM) in a computer cluster in which an unreliable underlying message passing technology is used, such that the DSM efficiently maintains coherency and reliability. DSM agents residing on different nodes of the cluster process access permission requests of local and remote users on specified data segments via handling procedures, which provide for recovering of lost ownership of a data segment while ensuring exclusive ownership of a data segment among the DSM agents detecting and resolving a no-owner messaging deadlock, pruning of obsolete messages, and recovery of the latest contents of a data segment whose ownership has been lost.

Abstract: Systems, Methods, and Computer Program Products are provided for performing concurrent checkpoints from file system agents residing on different nodes within in a clustered file system (CFS). Responsibility to checkpoint a modified and a committed data segment to a final storage location is assigned to one of the file system agents. One of the file system agents, which is assigned, is the file system agent whose associated distributed shared memory (DSM) agent is an owner of the data segment.

Abstract: Systems, Methods, and Computer Program Products are provided for concurrent checkpointing and modifications in a transactional clustered file system (CFS). Shadow data segments, whose contents are identical to an original data segment currently being written by a checkpoint operation, for users that require access for modification to data segments concurrently being written within a checkpoint operation.