Abstract: Embodiments are disclosed for a method. The method includes generating a backing layer having a file volume, in a layering file format and representing a portion of a volume snapshot that is backed up on a slower storage, and enabling an associated virtual machine. The method also includes generating an active layer comprising a second file volume, in the layering file format, representing a second portion of the volume snapshot, and enabling the associated virtual machine. The method further includes starting a process to pull a plurality of blocks from the backing layer to the active layer.

Abstract: Embodiments are disclosed for a method. The method includes generating a backing layer having a file volume, in a layering file format and representing a portion of a volume snapshot that is backed up on a slower storage, and enabling an associated virtual machine. The method also includes generating an active layer comprising a second file volume, in the layering file format, representing a second portion of the volume snapshot, and enabling the associated virtual machine. The method further includes starting a process to pull a plurality of blocks from the backing layer to the active layer.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression. A first compression is performed on a first set of data to create first compressed data. The first compressed data is stored in one or more blocks of a first compression group. A size of free space of a last block of the first compression group is discovered and calculated. A second compression is performed on a second set of data to create second compressed data. At least a portion of the second compressed data is supplied to the first compression group for padding into the last block in response to determining that the size of the free space is sufficient. An unpadded portion of the second compressed data is stored in one or more blocks of a second compression group.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression. A compression is performed on a first set of data to create a first set of compressed data partitions in a compression group. A partition table is constructed, and partition entries for the first data block are added to the table in conjunction with the first set. A current size of the compression group is assessed. In response to a compression ratio being greater than a target compression ratio and internal fragmentation of the compression group being smaller than a threshold, the compression group is dynamically completed. The dynamic completion decides a size for the compression group. The partition table is added to the compression group by assigning space within the first compression group for the table. The compression group is written to persistent storage.

Abstract: Autonomic compression including balancing performance of a compression technique and storage space savings in data storage based on an access characteristic is provided. The access characteristic of file data is determined including a read access and/or a write access. A space management action is dynamically selected to be applied to the file data. The selection automatically balances between a storage size and an access performance of the file data based on the access characteristic. The selected space management action is applied on the file data including changing a state of compression of the data.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression for efficient random access to the data. A first partition of a first data block of a compression group is compressed. The first compressed partition is stored in a first compression entity. An in-memory table is maintained, which includes updating the in-memory table with data associated with an address of the stored compressed first partition. At such time as it is determined that the first compression entity is full, the in-memory table is compressed and written to the first compression entity. Accordingly, the in-memory table, which stores partition compression data, is store with the compression entity.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression for efficient random access to the data. A first partition of a first data block of a compression group is compressed. The first compressed partition is stored in a first compression entity. An in-memory table is maintained, which includes updating the in-memory table with data associated with an address of the stored compressed first partition. At such time as it is determined that the first compression entity is full, the in-memory table is compressed and written to the first compression entity. Accordingly, the in-memory table, which stores partition compression data, is store with the compression entity.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression. A compression is performed on a first set of data to create a first set of compressed data partitions in a compression group. A partition table is constructed, and partition entries for the first data block are added to the table in conjunction with the first set. A current size of the compression group is assessed. In response to a compression ratio being greater than a target compression ratio and internal fragmentation of the compression group being smaller than a threshold, the compression group is dynamically completed. The dynamic completion decides a size for the compression group. The partition table is added to the compression group by assigning space within the first compression group for the table. The compression group is written to persistent storage.

Abstract: The embodiments described herein relate to managing compressed data to optimize file compression. A first compression is performed on a first set of data to create first compressed data. The first compressed data is stored in one or more blocks of a first compression group. A size of free space of a last block of the first compression group is discovered and calculated. A second compression is performed on a second set of data to create second compressed data. At least a portion of the second compressed data is supplied to the first compression group for padding into the last block in response to determining that the size of the free space is sufficient. An unpadded portion of the second compressed data is stored in one or more blocks of a second compression group.

Abstract: A write error detection mechanism for a computer data disk drive or storage controller writes and then verifies data to detect disk write errors. It allows the heads to be moved to other tracks to do other jobs in the time it takes the disk to rotate from the point the data was written and to return there again so it can be read to verify the write. The data written is temporarily stored in feature table memory outside the disk, so it can be used as in the comparison later when the written data can be read for the verify. In the interim, other write-and-verify and read operations can be pipelined, or multitasked using the same head, even on different tracks.

Abstract: A method and system for cache-based dropped write protection in data storage systems are provided. An implementation involves detecting undetected write errors in a storage system, by writing data to a storage medium from a data cache; maintaining a copy of the data in the data cache until said data on the storage medium is validated or said data needs to be evicted from the data cache; and prior to eviction of said data from the data cache, maintaining metadata for said data in a metadata cache until the data written to the storage medium has been validated against the metadata.

Abstract: A system and method is disclosed for maintaining, in a Storage Area Network (SAN), the consistency of a local copy of a remote file system sub-tree obtained from a remote source. Directory structure of the remote file system sub-tree is mapped to a remote container attached to the SAN and each remote object of the remote file system sub-tree is represented as a local object component of the remote container. Next, each of the local objects are labeled with attributes associated with the represented remote object, and metadata describing each of the local objects is stored in a metadata server. Also, a consistency policy is associated with each of the local objects in the remote container (wherein the policy defines conditions for checking freshness of said labeled attributes), and the local object components of remote container is updated in accordance with the consistency policy.

Abstract: Addressed is a system and method for remote data caching and replication by local copy maintenance of remote data within a SAN file system. Distributed Storage Tank (DST), an extension to a SAN file system, provides for transparent SAN client access of local copies by importing, exporting, and storing data using network file access protocols as well as by providing assurance of metadata and file content validity. A Remote Access Agent (RAA) handles protocol implementation and conversion necessary for communication with remote data sources. Controlled by a consistency policy, consistency is maintained by RAA fetching and updating local copies if modifications have occurred to a file since it was first stored as a local copy in local storage. Additionally, RAA returns metadata pertaining to the requested data. A SAN client obtains metadata corresponding to the requested data and utilizes it to directly access locally stored copies of remote data.

Abstract: A method and system for cache-based dropped write protection in data storage systems are provided. An implementation involves detecting undetected write errors in a storage system, by writing data to a storage medium from a data cache; maintaining a copy of the data in the data cache until said data on the storage medium is validated or said data needs to be evicted from the data cache; and prior to eviction of said data from the data cache, maintaining metadata for said data in a metadata cache until the data written to the storage medium has been validated against the metadata.

Abstract: A write error detection mechanism for a computer data disk drive or storage controller writes and then verifies data to detect disk write errors. It allows the heads to be moved to other tracks to do other jobs in the time it takes the disk to rotate from the point the data was written and to return there again so it can be read to verify the write. The data written is temporarily stored in feature table memory outside the disk, so it can be used as in the comparison later when the written data can be read for the verify. In the interim, other write-and-verify and read operations can be pipelined, or multitasked using the same head, even on different tracks.

Abstract: Network latencies are reduced by detecting a metadata access call for filesystem metadata contained in a filesystem node of remotely located filesystem. The metadata corresponding to the metadata access call is fetched when the metadata corresponding to the metadata access call is not contained in a local filesystem cache that has a hierarchical structure corresponding to a hierarchical structure of the remotely located filesystem. Metadata related to the metadata corresponding to the metadata access call from the remotely located filesystem is prefetched when the related metadata is not contained in the local filesystem cache. The metadata related to the metadata corresponding to the access call can be contained in a child node or a parent node of the node containing the metadata corresponding to the access call, or the descendants of such nodes.

Abstract: Network latencies are reduced by detecting a metadata access call for filesystem metadata contained in a filesystem node of remotely located filesystem. The metadata corresponding to the metadata access call is fetched when the metadata corresponding to the metadata access call is not contained in a local filesystem cache that has a hierarchical structure corresponding to a hierarchical structure of the remotely located filesystem. Metadata related to the metadata corresponding to the metadata access call from the remotely located filesystem is prefetched when the related metadata is not contained in the local filesystem cache. The metadata related to the metadata corresponding to the access call can be contained in a child node or a parent node of the node containing the metadata corresponding to the access call, or the descendants of such nodes.

Abstract: A system and method for defining a platform-independent policy framework for authentication of principals to servers in another realm, within a distributed data processing system. The present invention may be implemented on top of the Kerberos protocol, or any trusted third party network authentication protocol with inter-realm authentication mechanisms.