Abstract: Techniques for shrinking a filesystem backed by a volume identify slices in the volume to be evacuated in order to reach a target size, identify a target endpoint in the volume, and evacuate identified slices to available locations prior to the target endpoint. The same data is typically not moved from slice to slice multiple times.

Abstract: A method is used in managing stream connections in storage systems. A set of criteria is evaluated for managing flow control characteristics of a stream connection in a storage system. The flow control characteristics indicates the rate at which requests are processed by the stream connection. Based on the evaluation, management of the flow control characteristics is affected.

Abstract: A technique for managing storage space in a file system applies reference weights to compressed storage extents stored in multi-block segments. Each time a reference weight for a compressed storage extent in a segment changes to a value that indicates that the storage extent is no longer in use, a file system manager increments a freed-fragment counter provided for a range of the file system that includes the segment. The file system manager then determines whether to scavenge for free space in that range of the file system based at least in part on a count of the free-fragment counter.

Abstract: A technique for performing synchronous replication on both block and file-based objects employs a replication appliance embedded alongside a unified data path IO stack within a storage processor of a data storage system. Various arrangements are described for achieving failover, migration, failback, and load balancing, both involving other embedded replication appliances and involving external replication appliances.

Abstract: Examples are generally directed towards a file server having a unified file system associated with a unified slice map volume. In one example, the unified file system stores file system metadata and sparse volume metadata within the unified slice map volume. The unified file system performs a unified set of functions using the file system metadata and sparse volume metadata in the unified slice map volume.

Abstract: Improved techniques for storing data involve storing compressed data in blocks of a first AU size and storing uncompressed data in blocks of a second AU size larger than the first AU size. For example, when a storage processor compresses a chunk of data, the storage processor checks whether the compressed chunk fits in the smaller AU size. If the compressed chunk fits, then the storage processor stores a compressed chunk in a block having the smaller AU size. Otherwise, the storage processor stores the uncompressed chunk in a block having the larger AU size. Advantageously, the improved techniques promote better disk and cache utilization, which improves performance without disrupting block mapping.

Abstract: A data protection technique maintains replicas of both a data object and its snaps by conducting replication operations on the data object between a source and a destination. The technique includes generating a pair of content-consistent snaps, one snap of the data object at the source and one snap of its replica at the destination. A common snap signature identifies both snaps of the pair of content-consistent snaps. Orchestration of replication ensures that both snaps of the pair share the same content. The two snaps may thus be used interchangeably, with the snap of the replica at the destination providing essentially a backup of the snap of the data object at the source.

Abstract: A method is used in managing replication of file systems. Metadata of a set of slices of a file system is updated upon performing an operation on a slice of the file system. The file system includes the set of slices. The metadata of the set of slices is used for recovering the file system.

Abstract: A technique for performing non-disruptive migration coordinates object migration with snapshot-shipping to migrate both a data object and its snaps from a source to a target. Snapshot-shipping conveys snaps to the target, and an internal snap of the data object serves as a basis for building a migrated version of the data object at the target. As IO requests specifying writes to the data object arrive at the source, a data mirroring operation writes the arriving data both to the data object at the source and to the version thereof at the target. In parallel with the data mirroring operation, a filtering copy operation copies data of the internal snap to the target, but avoids overwriting data mirrored to the target after the internal snap is taken.

Abstract: A technique for repairing a RAID (Redundant Array of Independent Disks) group in a data storage system following a failure of a disk drive in the RAID group includes identifying regions of the failed disk drive that supported unallocated storage extents and writing predetermined data to corresponding regions of the spare disk drive. Any reading of other disk drives in the RAID group may thus be limited only to those regions of the failed disk drive that supported allocated storage extents.

Abstract: A technique performs replication. The technique involves receiving, by processing circuitry, a virtual storage processor (VSP) replication command from a user. The VSP replication command specifies a source VSP and a destination VSP (e.g., configuration data which defines an operating environment). The technique further involves identifying, by the processing circuitry and in response to the VSP replication command, multiple source data objects which are configured to store data from the context of the source VSP. The technique further involves automatically creating, after the multiple source data objects are identified, multiple replication sessions to replicate the multiple source data objects as multiple destination data objects which are configured to store data from the context of the destination VSP. Once created, the entire lifecycle of the replication session occurs at the VSP level and replication of the internals of the VSP are entirely hidden from the end user.

Abstract: A technique for managing file systems assigns groups of related files in a file system to respective version sets. Each version set includes all files of a file system that are related to one another by one or more snapshot operations. The technique provides a version set database, which stores, in connection with each version set, an identifier of each file that belongs to the respective version set. In an example, file system operations that require information about block sharing can perform lookup operations on the version set database to narrow the scope of files that are candidates for block sharing to those of a particular version set.

Abstract: Techniques for storing data received by a data storage system involve performing inline compression on received data and storing resulting compressed data in segments of contiguous physical address space of a file system. Each segment spans multiple contiguous physical addresses and stores data of multiple contiguous logical addresses of a file. Each segment has an extent list that provides a location within that segment of the compressed data for each logical address.

Abstract: A technique for managing transaction logging of file system metadata in a data storage system stores metadata transactions for multiple file systems of the data storage system in respective log files, such that each log file stores metadata transactions for a single file system only. The data storage system thus provides transaction log files on a per-file-system basis.

Abstract: A data storage system has one or more processing nodes, each processing node comprising memory coupled to processing circuitry, the one or more processing nodes running a set of virtualized filesystem managers (VFMs) having a shared namespace. The set of VFMs includes (a) a master VFM for managing a configuration filesystem stored on the persistent storage, the configuration filesystem storing configuration information for the set of VFMs and (b) a slave VFM for remotely mounting the configuration filesystem from the master VFM, the slave VFM obtaining details of its configuration from the remotely-mounted configuration filesystem, the slave VFM sharing the shared namespace with the set of VFMs, the shared namespace including a set of filesystems, each filesystem of the shared namespace being managed by a single VFM, and each filesystem of the shared namespace being accessible by the remote host through any of the VFMs of the set of VFMs.

Abstract: A technique for managing a data storage system that stores data in a set of RAID groups includes receiving IO requests specifying data to be written at different logical addresses and mapping the specified data to contiguous physical addresses, so as to produce contiguously-mapped data having a length equal to that of a full stripe of a RAID group. With data from the IO requests mapped to a contiguous, full-stripe range, the data storage system can write the data and its parity to a full stripe of the RAID group in a single set of operations.

Abstract: A method, computer program product, and computing system for receiving a storage operation request for a logical storage object. A storage insurance value is associated with the logical storage object. The storage operation request is processed to associate a storage liability value with the storage operation request. Whether the storage operation request should be effectuated is determined based, at least in part, upon the storage liability value and the storage insurance value.

Abstract: A method is used in managing log transactions in storage systems. A first portion of a transaction log space is allocated from a persistent journal associated with a file system to a first core of a multi-core storage processor and a second portion of the transaction log space is allocated from the persistent journal to a second core of the multi-core storage processor. A set of per-core bitmaps is used for allocating a set of transaction log entries from the persistent journal. Each per-core bitmap is associated with a respective core of the multi-core storage processor. A per-core bitmap of the set of per-core bitmaps associated with a core of the multi-core storage processor is used for allocating a transaction log entry for a write request performed by the core.

Abstract: A technique for storing support files in a data storage apparatus provides auxiliary files in a container file system. The container file system stores a container file that provides a file-based realization of a data object, such as an entire file system, LUN, or vVOL, for example, and stores one or more auxiliary files in the container file system alongside the container file. Thus, an auxiliary file that supports an application program's operations on a data object resides in the same fault domain with the container file that realizes the data object.

Abstract: A method is used in managing file system checking. A logical space is created from a set of cylinder groups. The logical space includes respective unused blocks in each cylinder group of the set of cylinder groups. Each cylinder group of the set of cylinder groups is configured to store metadata and data of a file system. Information required to perform file system checking on the file system is stored in the logical space. File system checking is performed on the file system.