Abstract: Embodiments of the invention relate to optimizing the storage of data in a multi-cache level environment. In one aspect, data is classified into primary and secondary cache sections. Data is differentiated based on an inherent sharing characteristic of the data within a system comprising virtual machines. The data is then placed into the classified sections of the cache storage layer and/or persistent data, reflective of how the data is shared among virtual disk images access by virtual machines.

Abstract: Embodiments of the invention relate to supporting transaction data committed to a stable storage. Committed data in the cluster is stored in the persistent cache layer and replicated and stored in the cache layer of one or more secondary nodes. One copy is designated as a master copy and all other copies are designated as replica, with an exclusive write lock assigned to the master and a shared write lock extended to the replica. An acknowledgement of receiving the data is communicated following confirmation that the data has been replicated to each node designated to receive the replica. Managers and a director are provided to support management of the master copy and the replicas within the file system, including invalidation of replicas, fault tolerance associated with failure of a node holding a master copy, recovery from a failed node, recovered of the file system from a power failure, and transferring master and replica copies within the file system.

Abstract: Embodiments of the invention relate to supporting transaction data committed to a stable storage. Committed data in the cluster is stored in the persistent cache layer and replicated and stored in the cache layer of one or more secondary nodes. One copy is designated as a master copy and all other copies are designated as replica, with an exclusive write lock assigned to the master and a shared write lock extended to the replica. An acknowledgement of receiving the data is communicated following confirmation that the data has been replicated to each node designated to receive the replica. Managers and a director are provided to support management of the master copy and the replicas within the file system, including invalidation of replicas, fault tolerance associated with failure of a node holding a master copy, recovery from a failed node, recovered of the file system from a power failure, and transferring master and replica copies within the file system.

Abstract: Embodiments of the invention related to a switch-aware parallel file system. A computing cluster is partitioned into a plurality of computing cluster building blocks comprising a parallel file system. Each computing cluster building block comprises a file system client, a storage module, a building block metadata module, and a building block network switch. The building block metadata module tracks a storage location of data allocated by the storage module within the computing cluster building block. The computing cluster further comprises a file system metadata module that tracks which of the plurality of computing cluster building blocks data is allocated among within the parallel file system. The computing cluster further comprises a file system network switch to provide the parallel file system with access to each of the plurality of computing cluster building blocks and the file system metadata module.

Abstract: Methods, systems, and computer program products are provided for performing a secure delete operation in a wide area network (WAN) including a cache site and a home site. A method includes identifying a file for deletion at the cache site, determining whether the file has a copy stored at the home site, detecting a location of the copy at the home site prior to a disconnection event of the cache site from the home site, deleting the file from the cache site during the disconnection event, and performing a secure deletion of the copy at the home site immediately after a reconnection event of the cache site to the home site.

Abstract: Embodiments of the invention relate to efficiently employing checksums for shared nothing clustered filesystems. Tools are provided to compute the checksum in response to a read transaction and to utilize the computed checksum to prevent serving corrupted data. Multiple levels of data replication are provided. The checksum computation functions within the multiple levels and addresses a specified data block that is the subject of the read transaction.

Abstract: Asynchronous file operations in a scalable multi-node file system cache for a remote cluster file system, is provided. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching local file data in the cache by fetching file data on demand from the remote cluster file system into the cache over the network. The local file data corresponds to file data in the remote cluster file system. Local file information is asynchronously committed from the cache to the remote cluster file system over the network.

Abstract: Asynchronous file operations in a scalable multi-node file system cache for a remote cluster file system, is provided. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching local file data in the cache by fetching file data on demand from the remote cluster file system into the cache over the network. The local file data corresponds to file data in the remote cluster file system. Local file information is asynchronously committed from the cache to the remote cluster file system over the network.

Abstract: Facilitating access to data in a network, is provided. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching file data in a cache by fetching file data on demand from a remote cluster file system into the local cached file system over the network. The local file data corresponds to file data in the remote cluster file system. Upon disconnection from the remote cluster file system, all file operations are supported at the cache. Then, upon reconnection to the remote cluster file system over the network, the remote cluster file system is synchronized with the information cached in the cache during the disconnection even in the presence of failures.

Abstract: Directory traversal in a scalable multi-node file system cache for a remote cluster file system, is provided. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching local file data in the cache by fetching file data on demand from a remote cluster file system into the cache over the network. The local file data corresponds to file data in the remote cluster file system. The local namespace emulates the remote namespace and is created on demand. Access to data further involves performing directory traversal for the cache for the remote cluster file system by creating a directory structure on demand.

Abstract: Embodiments of the invention relate to synchronization of data in a shared pool of configurable computer resources. An image of the filesystem changes, including data and metadata, is captured in the form of a consistency point. Sequential consistency points are created, with changes to data and metadata in the filesystem between sequential consistency captured and placed in a queue for communication to a target filesystem at a target site. The changes are communicated as a filesystem operation, with the communication limited to the changes captured and reflected in the consistency point.

Abstract: Embodiments of the invention relate to synchronization of data in a shared pool of configurable computer resources. An image of the filesystem changes, including data and metadata, is captured in the form of a consistency point. Sequential consistency points are created, with changes to data and metadata in the filesystem between sequential consistency captured and placed in a queue for communication to a target filesystem at a target site. The changes are communicated as a filesystem operation, with the communication limited to the changes captured and reflected in the consistency point.

Abstract: Embodiments of the invention relate to creating and maintaining consistent data sets in a shared pool of configurable computer resources to support disaster recovery support. Data from an application is stored in local data storage and replicated to another data storage. A consistency point of the data is created in both of the data storage, with the consistency point representing an identical data set at a point-in-time. Based upon the created consistency points, a consistent set of application data may be requested to support a read operation for a migrated application.

Abstract: Embodiments of the invention relate to creating and maintaining consistent data sets in a shared pool of configurable computer resources to support disaster recovery support. Data from an application is stored in local data storage and replicated to another data storage. A consistency point of the data is created in both of the data storage, with the consistency point representing an identical data set at a point-in-time. Based upon the created consistency points, a consistent set of application data may be requested to support a read operation for a migrated application.

Abstract: Asynchronous file operations in a scalable multi-node file system cache for a remote cluster file system, is provided. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching local file data in the cache by fetching file data on demand from the remote cluster file system into the cache over the network. The local file data corresponds to file data in the remote cluster file system. Local file information is asynchronously committed from the cache to the remote cluster file system over the network.

Abstract: Scalable caching of remote file data in cluster file systems is provided. One implementation involves maintaining a cache in a local cluster file system and caching local file data in the cache by fetching file data on demand from the remote cluster file system into the local cached file system over the network. The local file data and metadata corresponds to the remote file data and metadata in the remote cluster file system. Updates made to the local file data and metadata are pushed back to the remote cluster file system asynchronously.

Abstract: A method for disk image access in a storage system comprises receiving an input/output (I/O) request to a disk image in a file system of a storage system, and in response to the I/O request to the disk image in the file system, reconstructing a file system request. Introspection is performed on the disk image to determine an original file system request based on the I/O request to the disk image. The method further includes laying out a disk image in the file system of the storage system, and performing type-specific introspection on the disk image. Based upon the results of the introspection, data ranges in the disk image are mapped to block or files within the file system. A mapping of disk image data ranges to block or files in the file system is maintained for responding to further I/O requests.

Abstract: Embodiments of the invention relate to dynamic application migration in a shared pool of configurable computer resources with disaster recovery support. Data from an application is replicated from local data storage to remote data storage. A consistency point of the data is created in both the local data storage and the remote data storage. The application may be migrated to a second data site with separate local data storage. The migration may be planned or unplanned. Based upon the created consistency point, a consistent set of application data may be requested to support a read operation from the migrated application.

Abstract: A system for ensuring data integrity, comprising a plurality of data servers configured in a GPFS configuration, the plurality of data servers comprising an application server comprising a application server fileset, a home server comprising a home server fileset and a gateway server comprising a gateway fileset, a connection monitor node (CMN) coupled to gateway server; and logic, executed by the CMN, for monitoring a connection between the home server and the application server; and if the connection is disconnected, executing logic for comparing a duration of the connection disconnect to a expiration timeout attribute corresponding to the application server fileset and if the duration exceeds the expiration timeout attribute, notifying the application server to set an expiration status attribute in the application fileset.

Abstract: Embodiments of the invention related to a switch-aware parallel file system. A computing cluster is partitioned into a plurality of computing cluster building blocks comprising a parallel file system. Each computing cluster building block comprises a file system client, a storage module, a building block metadata module, and a building block network switch. The building block metadata module tracks a storage location of data allocated by the storage module within the computing cluster building block. The computing cluster further comprises a file system metadata module that tracks which of the plurality of computing cluster building blocks data is allocated among within the parallel file system. The computing cluster further comprises a file system network switch to provide the parallel file system with access to each of the plurality of computing cluster building blocks and the file system metadata module.