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: An identification system that may be used in heterogeneous computing environments provides a fail-free path to providing identifiers from a single canonical namespace. Objects or gateways requiring an identifier for access are accessed using an identifier for the canonical namespace. If an entity requests access using an identifier from another namespace, an external database is consulted to determine if a mapping exists for the identifier to another identifier the canonical namespace. If no mapping exists, or the external database is unavailable, then an identifier is automatically generated in the canonical namespace and is used for the access. An internal database is updated with the automatically generated identifier, providing a mechanism to add mappings without administrative intervention. To access resources requiring an identifier from another particular namespace, a canonical namespace identifier may be mapped to another identifier in the particular namespace, or a generic identifier may be used.

Abstract: An identification system that may be used in heterogeneous computing environments provides a fail-free path to providing identifiers from a single canonical namespace. Objects or gateways requiring an identifier for access are accessed using an identifier for the canonical namespace. If an entity requests access using an identifier from another namespace, an external database is consulted to determine if a mapping exists for the identifier to another identifier the canonical namespace. If no mapping exists, or the external database is unavailable, then an identifier is automatically generated in the canonical namespace and is used for the access. An internal database is updated with the automatically generated identifier, providing a mechanism to add mappings without administrative intervention. To access resources requiring an identifier from another particular namespace, a canonical namespace identifier may be mapped to another identifier in the particular namespace, or a generic identifier may be used.

Abstract: A technique for restoring file systems by applying full and incremental backups together while streaming them from multiple devices provides a faster system restore from a full backup where incremental backups must also be applied. A first storage device streams the full backup while at least one second storage device streams at least one incremental backup. As files are detected in the incremental backup, they are written instead of the corresponding file in the full backup. Incremental backups can be pre-merged to reduce their number to one less than a number of storage devices available to stream the backups, so that the full backup can be streamed along with the pre-merged incremental backup(s) to restore the file system.

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, system, and computer program product for creating and implementing file clones using reverse ditto references. A clone inode is created as a copy of an original inode. The clone inode and the original inode are indistinguishable to an end user. Each additional file clone created spawns a clone inode. An immutable clone-parent inode is created that contains the disk block addresses, while writable clones inode instead contain dittos linking the clone inode to data blocks referenced in the clone-parent inode. Data block address links in the original inode are moved to the new clone-parent inode and dittos replace the original data block address links in the original inode. When a clone file is updated, the new data is written to a new disk location and a corresponding ditto in the clone inode is replaced with a data block link address, keeping the data of the clone-parent inode intact.

Abstract: A method for avoiding directory conflicts across a file system having multiple nodes with one node representing a token manager. For each directory, at least one metanode responsible for directory updates. The method involving obtaining a name-based lock on a filename. Querying the token manager for a lock token. If a new token is obtained, sending a Remote Procedure Call (RPC) to the metanode to obtain matching directory entries, and caching the result of the RPC so that subsequent operations on that filename can be satisfied without additional messages sent to the metanode. Updating a cached directory block in memory by creating a new directory entry in the block or deleting an existing directory entry from the block. Information regarding the updating is sent to the metanode on one of: periodic schedule, a subsequent synchronization event, or when the name-based lock token is revoked.

Abstract: A selective restore technique for restoring file systems within computer systems provides on-demand access during the restore process, while preventing users from slowing the restore process by generating random accesses to files that have not yet been restored, early in the restore process. The restored files are grouped into multiple groups of files, which correspond to multiple phases of the restore process. On-demand requests may be locked out for some or all users during the first one or more phases of the restore, while they are permitted for the subsequent phases, ensuring that critical files needed by all users will be available before the backup process is interrupted by on-demand accesses. The groups are generally organized by elapsed time since last access or modification, and may be organized at restore time or during periodic back-up operations so that the files may be similarly organized in the backup media.

Abstract: An identification system that may be used in heterogeneous computing environments provides a fail-free path to providing identifiers from a single canonical namespace. Objects or gateways requiring an identifier for access are accessed using an identifier for the canonical namespace. If an entity requests access using an identifier from another namespace, an external database is consulted to determine if a mapping exists for the identifier to another identifier the canonical namespace. If no mapping exists, or the external database is unavailable, then an identifier is automatically generated in the canonical namespace and is used for the access. An internal database is updated with the automatically generated identifier, providing a mechanism to add mappings without administrative intervention. To access resources requiring an identifier from another particular namespace, a canonical namespace identifier may be mapped to another identifier in the particular namespace, or a generic identifier may be used.

Abstract: A method for avoiding directory conflicts across a file system having multiple nodes with one node representing a token manager. For each directory, at least one metanode responsible for directory updates. The method involving obtaining a name-based lock on a filename. Querying the token manager for a lock token. If a new token is obtained, sending a Remote Procedure Call (RPC) to the metanode to obtain matching directory entries, and caching the result of the RPC so that subsequent operations on that filename can be satisfied without additional messages sent to the metanode. Updating a cached directory block in memory by creating a new directory entry in the block or deleting an existing directory entry from the block. Information regarding the updating is sent to the metanode on one of: periodic schedule, a subsequent synchronization event, or when the name-based lock token is revoked.

Abstract: A method for data access in a multinode, shared storage data processing environment is provided by enhancing the file locking mechanism structure so as to permit nodes not normally designated as metadata controller nodes to fulfill that function for limited times thus at least temporarily eliminating the need for continual node-to-node coordination. This is particularly advantageous in the access and transfer of large files such as video files or files containing complex visualization data.

Abstract: An identification system that may be used in heterogeneous computing environments provides a fail-free path to providing identifiers from a single canonical namespace. Objects or gateways requiring an identifier for access are accessed using an identifier for the canonical namespace. If an entity requests access using an identifier from another namespace, an external database is consulted to determine if a mapping exists for the identifier to another identifier the canonical namespace. If no mapping exists, or the external database is unavailable, then an identifier is automatically generated in the canonical namespace and is used for the access. An internal database is updated with the automatically generated identifier, providing a mechanism to add mappings without administrative intervention. To access resources requiring an identifier from another particular namespace, a canonical namespace identifier may be mapped to another identifier in the particular namespace, or a generic identifier may be used.

Abstract: A computer-implemented method enables efficient tracking of fileset IDs and inode utilizing a fileset mask and an internal inode mask. A utility dynamically updates the fileset mask and the internal inode mask to enable mapping of the number of one (1) bits in the fileset mask to a fileset identifier (ID) and mapping of the one bits in the inode mask to an inode number for the fileset, as either the number of filesets or the number of inodes required per filesets increases above a next power of two threshold. The one bits within the fileset mask and the internal inode mask are disjoint relative to each other. An external inode number is mapped to a corresponding fileset and to a corresponding inode number by concatenating individual bits of the external inode number corresponding to each one (1) bit within the fileset mask and the inode mask.

Abstract: A method, system, and computer program product for creating and implementing file clones using reverse ditto references. A clone inode is created as a copy of an original inode. The clone inode and the original inode are indistinguishable to an end user. Each additional file clone created spawns a clone inode. An immutable clone-parent inode is created that contains the disk block addresses, while writable clones inode instead contain dittos linking the clone inode to data blocks referenced in the clone-parent inode. Data block address links in the original inode are moved to the new clone-parent inode and dittos replace the original data block address links in the original inode. When a clone file is updated, the new data is written to a new disk location and a corresponding ditto in the clone inode is replaced with a data block link address, keeping the data of the clone-parent inode intact.

Abstract: An identification system that may be used in heterogeneous computing environments provides a fail-free path to providing identifiers from a single canonical namespace. Objects or gateways requiring an identifier for access are accessed using an identifier for the canonical namespace. If an entity requests access using an identifier from another namespace, an external database is consulted to determine if a mapping exists for the identifier to another identifier the canonical namespace. If no mapping exists, or the external database is unavailable, then an identifier is automatically generated in the canonical namespace and is used for the access. An internal database is updated with the automatically generated identifier, providing a mechanism to add mappings without administrative intervention. To access resources requiring an identifier from another particular namespace, a canonical namespace identifier may be mapped to another identifier in the particular namespace, or a generic identifier may be used.

Abstract: A method is provided for managing the storage of a file that has been selected for migration from a first storage level within a file system to a second storage level. The method comprises copying each of one or more data blocks of the selected file that are stored in the first storage level at a physical disk address maintained in a corresponding reference of an inode for the selected file from the first storage level to the second storage level; maintaining a logical ditto address in each reference of an inode for each snapshot file in the file system that refers to one of the one or more data blocks of the selected file that were copied to the second storage level; and updating the file system to include a managed region for controlling access to the one or more data blocks through the inode for the selected file.