Abstract: A technique for managing storage space includes establishing an MSR (minimum space reservation) of a thin file system built upon a storage pool. In response to a set of storage requests to the file system to store new data, the method further includes obtaining an additional space guarantee from the storage pool. After deleting data from the file system such that the size of the file system falls below the MSR, the technique further includes performing a space reclaim operation, the space reclaim operation (i) compacting the file system to a size less than the MSR, (ii) canceling the additional space guarantee such that the storage pool no longer guarantees the additional space for the file system, and (iii) continuing to reserve the full MSR of the file system, even though the size of the file system is smaller than the MSR.

Abstract: Techniques for limiting storage consumed by a file system without shrinking a volume upon which the file system is deployed. The techniques are employed in a clustered environment including multiple NAS nodes, each having access to block storage including multiple storage devices. By deploying the file system on a volume of a NAS node within the clustered environment, setting the value of the FS user size to be equal to the FS volume size, and if, at a later time, it is desired to reduce the file system size, setting the value of the FS user size to a lesser value than the FS volume size, IO requests received at the NAS node can be satisfied within the logical limit of the lesser value of the FS user size without shrinking the local volume, allowing the file system size to be reduced without requiring close coordination with the block storage.

Abstract: A technique for managing storage space in a data storage system generates liability values on a per-family basis, with each family including files in the file system that are related to one another by snapping. Each family thus groups together files in the file system that generally share at least some blocks among one another based on snapshot activities. Distinct files that do not share blocks based on snapping are provided in separate families. The technique further generates worst-case storage liability of a version family by differentiating between writable data objects and read-only data objects, thus allowing administrators to provide spare storage and/or prepare for increases in storage requirements as writable data objects grow and differentiate.

Abstract: Techniques for improving storage efficiency of a data storage system are provided. The techniques include (a) performing a testing operation to evaluate whether a test condition is satisfied for a filesystem having a plurality of subspaces, each subspace being provisioned with a respective amount of storage, each subspace of the filesystem being dedicated to storing different respective types of filesystem content, wherein the test condition indicates that a first subspace has available space in excess of a threshold percentage, (b) in response to determining that the test condition is satisfied for the filesystem, performing a reduction operation on the first subspace to remove a portion of storage provisioned to that subspace while retaining the removed portion for use by the filesystem, and (c) upon a second subspace reaching a fullness threshold, provisioning the removed portion to the second subspace and storing content of the respective type of the second subspace thereon.

Abstract: A technique for managing storage space in a data storage system implements data objects in respective files. In response to an instruction to convert a set of such files from thin to thick or from thick to thin, the data storage system checks whether it has enough available storage space to accommodate the set of files if conversion were to proceed. If so, conversion is performed, and each of the set of files is converted from thin to thick or from thick to thin, in accordance with the instruction.

Abstract: Techniques for limiting storage consumed by a file system without shrinking a volume upon which the file system is deployed. The techniques are employed in a clustered environment including multiple NAS nodes, each having access to block storage including multiple storage devices. By deploying the file system on a volume of a NAS node within the clustered environment, setting the value of the FS user size to be equal to the FS volume size, and if, at a later time, it is desired to reduce the file system size, setting the value of the FS user size to a lesser value than the FS volume size, IO requests received at the NAS node can be satisfied within the logical limit of the lesser value of the FS user size without shrinking the local volume, allowing the file system size to be reduced without requiring close coordination with the block storage.

Abstract: A technique for facilitating file system operations in a data storage system provides multiple version family databases. Each version family database identifies members of a respective version family, i.e., a respective set of files in a file system that are related by file snapping. When a snap of a file is created, the file system updates a version family database for the version family that includes the file, such that the version family database identifies both the file and the snap.

Abstract: A technique for managing host data in a data storage apparatus having a storage processor (SP) provides virtualized storage processors (VSPs) as substantially self-describing and independent entities. Each VSP has its own namespace, independent of the namespace of any other VSP. Each VSP also has its own network address. Hosts may thus access VSPs directly, without having to include path information relative to the SP on which the VSP is operated. VSPs can thus be moved from one physical SP to another with little or no disruption to hosts, which may continue to access the VSPs on the new SPs using the same paths as were used when the VSPs were running on the original SPs.

Abstract: A data inconsistency is detected in a file system data block of a file system. The file system includes a set of files, each file includes a set of file system data blocks. Information regarding a file including 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: Techniques for improving storage efficiency of a data storage system are provided. The techniques include (a) performing a testing operation to evaluate whether a test condition is satisfied for a filesystem having a plurality of subspaces, each subspace being provisioned with a respective amount of storage, each subspace of the filesystem being dedicated to storing different respective types of filesystem content, wherein the test condition indicates that a first subspace has available space in excess of a threshold percentage, (b) in response to determining that the test condition is satisfied for the filesystem, performing a reduction operation on the first subspace to remove a portion of storage provisioned to that subspace while retaining the removed portion for use by the filesystem, and (c) upon a second subspace reaching a fullness threshold, provisioning the removed portion to the second subspace and storing content of the respective type of the second subspace thereon.

Abstract: A method is used in managing migration of virtual file servers. The method migrates a virtual file server from a source storage processor to a destination storage processor in a storage system. The storage system includes the source and the destination storage processors. The virtual file server comprises a root file system, a configuration file system, and a set of user file systems. The method enables concurrent access to the root file system from both source and destination storage processors during the migration until the set of user file systems is migrated from the source storage processor to the destination storage processor.

Abstract: A technique for managing file system expansions includes receiving a request to perform a file system expansion, the request specifying or implying an increase in size of a file system to a new target size. The request is received while a previous file system expansion is already in progress. The technique includes merging the previous file system expansion into the file system expansion specified by the request, to increase the size of the file system to the new target size.

Abstract: An improved technique involves providing file system shrink capability by shrinking the size of the volume file in which an upper deck file system is stored. Along these lines, a data storage system, upon receiving a request to shrink an upper deck file system, determines a new address in the upper deck file system, based on an amount the upper deck file system is to be shrunk, to which the end-of-file (EOF) pointer of the volume file will point. The new address will have a smaller distance from the address of the file pointer than the original address to which the EOF pointer points. The data storage system then identifies nonempty data blocks of the upper deck file system that have logical addresses having a larger distance from the address of the file pointer than the second logical address.

Abstract: A method is used in managing data inconsistencies in files of file systems. A data inconsistency is detected in a file system data block of a file system. The file system includes a set of files, each file includes a set of file system data blocks. Information regarding a file including 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 technique for managing storage space in a data storage system generates liability values on a per-family basis, with each family including files in the file system that are related to one another by snapping. Each family thus groups together files in the file system that share at least some blocks among one another based on snapshot activities. Distinct files that do not share blocks based on snapping are provided in separate families. The file system leverages the snap-based relationships among family members to produce more accurate estimates of liability than would otherwise be feasible.

Abstract: A method includes (a) receiving a command to create an upper-deck filesystem of a specified size, the upper-deck filesystem residing within a logical volume expressed from a container file of a lower-deck filesystem, (b) provisioning a plurality of storage provisioning units (SPUs) from a storage pool of the data storage system to the container file in an order reflecting proximity of the SPUs within storage devices of the data storage system, the plurality of SPUs providing storage for the entire container file, and (c) subsequent to provisioning the plurality of SPUs to the container file, executing a plurality of threads in parallel to write metadata of the upper-deck filesystem to the plurality of SPUs, representing the upper-deck filesystem. Other embodiments are directed to a system, a computerized apparatus, and a computer program product for performing methods similar to that described above.

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 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 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 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.