Abstract: Aspects related to a resource-constrained system are described herein that can provide object storage services after a service interruption is resolved, even if all of the transactions that were pending and incomplete prior to the service interruption have not yet been recovered and/or executed. For example, file systems implemented by computing systems of the resource-constrained system may treat each file or directory as a separate object. Thus, a transaction directed to one file may not affect the file's directory or other files in the directory. As a result, the resource-constrained system can achieve read-after-write consistency without first recovering and executing the pending, incomplete transactions. Instead, read-after-write consistency for an object can be achieved simply by completing any pending, incomplete transaction directed to that object.

Abstract: A method, computer program product, and computing system for receiving a first write request on a front-end computing system within a storage system. The first write request concerns writing a first data portion to a storage array within the storage system. A first log entry is generated within a journal file. The first log entry identifies a first differential storage quantity associated with storing the first data portion in the storage array within the storage system.

Abstract: A method is used in managing data inconsistencies in file systems. A data inconsistency is detected in a file system data block of a file system. The file system includes a set of file system data blocks. Information regarding the data inconsistency is provided to a client of the file system. Based on the information, the client is enabled to determine an action for recovering from the data inconsistency.

Abstract: A method is used in managing file system checking in file systems. Metadata of a file system is evaluated upon receiving a request to perform file system checking on the file system. Based on the evaluation, determination is made as to whether file system checking has been performed previously on the file system. Based on the determination, file system checking is performed on the file system.

Abstract: A method is used in recovering file mapping information in file systems. Metadata of a file of a file system is evaluated. Mapping information associating the file to a file system hierarchy of the file system is missing a reference to an inode of the file. Based on the evaluation, the mapping information is updated for including the file to the file system hierarchy of the file system.

Abstract: A slice consistency check method is presented including, for each slice of a plurality of slices (a) obtaining a first vote for ownership of that slice according to a filesystem manager configured to manage a set of filesystems stored on a set of sparse metavolumes, (b) obtaining a second vote for the ownership of that slice according to a first driver, the first driver being independent of the filesystem manager, (c) obtaining a third vote for the ownership of that slice according to a second driver, the second driver being independent of the filesystem manager and the first driver, and (d) assigning ownership of that slice based on a majority vote of the first vote for the ownership of that slice, the second vote for the ownership of that slice, and the third vote for the ownership of that slice.

Abstract: An improved technique involves providing read-only access to the file system while FSCK is running. After a storage processor detects corrupted data in the file system, the storage processor brings the file system offline and provides FSCK with read-only access to the file system. The storage processor then begins a repair process on the disk by starting to run FSCK, which writes corrupted blocks to a secondary storage device. Upon receiving a request from a user for access to a file in the file system, the storage processor mounts the file system with read-only access. Upon completion of FSCK, the storage processor brings the file system offline, applies the corrected blocks from secondary storage to the blocks in primary storage, and brings the file system online with full read and write access.

Abstract: A method is used in recovering duplicate blocks in file systems. A duplicate file system block is detected in a file system. The duplicate file system block is referred by a first inode associated with a first file of the file system and a second inode associated with a second file of the file system. Metadata of the duplicate file system block is evaluated. Based on the evaluation, a set of inodes in the file system is determined. Each inode of the set of inodes refer to the duplicate file system block. Based on the determination, the set of inodes is updated.

Abstract: A method is used in recovering file system blocks of file systems. A first read error is encountered upon reading a file system block of a file system. The file system block includes a first set of chunks. A second read error is encountered upon reading a duplicate copy of the file system block. The duplicate copy of the file system block includes a second set of chunks. Each chunk of the first and second sets of chunks is evaluated. Based on the evaluation, the file system block is recovered.

Abstract: A method is used in analyzing mapping objects of file systems. Each mapping object of a set of mapping objects of files of a file system is analyzed by iterating over the set of mapping objects. A file is associated with a first mapping object of the set of mapping objects and a snapshot copy of the file is associated with a second mapping object of the set of mapping objects. The second mapping object shares a subset of a set of storage objects associated with the first mapping object. Information for each storage object of the set of storage objects associated with each mapping object of the set of mapping objects is stored. Based on the stored information, each storage object of the set of storage objects associated with each mapping object of the set of mapping objects is processed.

Abstract: A method, system, apparatus, and computer-readable medium are provided for performing read-ahead operations for sequential read operations. A method includes maintaining a bitmap including a plurality of bits, each bit corresponding to a sector of the disk cache and containing data indicating whether the corresponding sector is valid and can be used to satisfy read requests. The method includes receiving a request to read a sector of the disk cache, and in response, identifying a bit in the bitmap that corresponds to the requested sector. Further, the method includes determining whether the disk cache contains valid data for a sector previous to the requested sector by examining a bit in the bitmap previous to the bit that corresponds to the requested sector, and in response, reading sequentially into the disk cache sectors of the disk cache corresponding to bits in the bitmap following the bit corresponding to the requested sector.

Abstract: A method is used in recovering files in data storage systems. A set of file system blocks of a file of a file system is identified. The set of file system blocks are associated with a portion of an inode of the file of the file system. Mapping information associated with the portion of the inode is missing references to the set of file system blocks. Metadata of each file system block of the set of file system blocks is evaluated. Based on the evaluation, the portion of the inode of the file is recovered by updating mapping information associated with the portion of the inode.

Abstract: A method, system, apparatus, and computer-readable medium are provided for implementing caching in a data storage system. According to aspects of the invention, a cache module is provided that utilizes cache lines sized according to a snapshot chunk size or an allocation unit size. The cache module utilizes cache header data structures corresponding to cache lines, each of which is assigned a device and logical block access range when active. The active headers are arranged in a set of hash queues. A free queue corresponds to the list of unused cache headers and a dirty queue corresponding to a list of unflushed cache headers. The cache header contains sector-level bitmaps of the cache line, specifying on a per sector granularity the bits that are dirty and valid. Flushing is performed by copying the dirty bitmap into a temporary memory location and flushing the bits set in it, while resetting the dirty bitmap and allowing writes to it.

Abstract: According to one embodiment of the present invention, a substrate arrangement is provided. The substrate arrangement includes a first substrate; a second substrate positioned above the first substrate, the second substrate comprising a first through hole; a third substrate positioned above the second substrate, the third substrate comprising a second through hole; a first electrically conductive interconnect pillar positioned on the first substrate and extending from the first substrate through the first through hole to electrically contact the third substrate; and a second electrically conductive interconnect pillar positioned on the second substrate and extending from the second substrate through the second through hole. A method of manufacturing a substrate arrangement is also provided.

Abstract: A die package and a method for manufacturing the die package are provided.

Abstract: A method, system, apparatus, and computer-readable medium are provided for storing data at a virtual tape library (“VTL”) computer or server. According to one method, a VTL computer maintains one or more storage volumes for use by initiators on an array of mass storage devices. Space on each of the volumes is allocated using thin provisioning. The VTL computer may also include a cache memory that is at least the size of a full stripe of the array. Write requests received at the VTL computer are stored in the cache memory until a full stripe of data has been received. Once a full stripe of data has been received, the full stripe of data is written to the array at once. The array utilized by the VTL computer may include a hot spare mass storage device. When a failed mass storage device is identified, only the portions of the failed device that have been previously written are rebuilt onto the hot spare. The array may be maintained using RAID-5.

Abstract: Technologies are presented herein for synchronization of I/O operations in a data storage system. Multiple reader and writer locks may be acquired by calling processes at two different granularities. Locks may be acquired for an area of storage equivalent to the logical unit of allocation or for a sub-provision area equivalent to a unit of snapshot read-modify-write. Each lock may be represented by a lock data structure that represents the same amount of logical address space as the logical unit of allocation. A request that arrives to the lock data structure may be placed in a lock wait queue until the request can be honored. A round robin technique may be utilized to respond to requests for locks so that one lock does not starve out other locks.

Abstract: A method, system, apparatus, and computer-readable medium are provided for synchronizing I/O operations in a computer system. According to aspects of the invention, multiple reader and writer locks are provided that may be acquired by calling processes at two different granularities. Locks may be acquired for an area of storage equivalent to the logical unit of allocation or for a sub-provision area equivalent to a unit of snapshot read-modify-write. Each lock is represented by a lock data structure that represents the same amount of logical address space as the logical unit of allocation. A request that arrives to the lock data structure is made to wait in a lock wait queue until the request can be honored. Requests that have been honored but that have not yet released the lock are maintained in a dispatch queue. When a writer lock is assigned to a lock request, no other readers or writers may be allocated to it.

Abstract: A method for micro-component self-assembly is disclosed. An embodiment self-assembly method provides a substrate with an interconnect, and a micro-device having a corresponding interconnect that is arranged for engagement with the interconnect of the substrate during the self-assembly process. A method for fabricating a micro-device for micro-component self-assembly with a substrate and a method for fabricating a substrate for micro-component self-assembly with a micro-device are also disclosed.