Abstract: A data storage system can include a deduplicated data cache used to store unique deduplicated data portions. Data portions can be promoted to the deduplicated data cache in connection with servicing I/O operations. Servicing the I/O operation that reads data from, or writes data to, a logical address can include determining whether a data portion stored at the logical address meets criteria for promoting the data portion to a deduplicated data cache. The criteria can include a condition that the data portion is a duplicate of content stored at multiple logical addresses, and can include a condition that the data portion has a reference count that is at least a minimum threshold where the reference count denotes a number of logical addresses at which the data portion is stored. Responsive to determining the data portion meets the criteria, the data portion can be stored in the deduplicated data cache.

Abstract: A method is used for managing overlapping communications regarding downtiering and invalidating cached data among nodes in a storage system. The method includes identifying, by a node, data to downtier. The node adds the data to an in progress table, and sends a request for permission to downtier the data to a peer node. The node receives permission from the peer node to downtier the data. In response to the permission to downtier the data, the node checks the in progress table for the data and takes an action based on a result of checking the in progress table.

Abstract: A technique for managing a mapping structure in a data storage system includes identifying levels in the mapping structure of pages to be removed and estimating the workload required for removing the pages based at least in part on the identified levels. The technique further includes initiating processing of the pages based at least in part on the estimated workload.

Abstract: A method is used for managing overlapping communications regarding downtiering and invalidating cached data among nodes in a storage system. The method includes identifying, by a node, data to downtier. The node adds the data to an in progress table, and sends a request for permission to downtier the data to a peer node. The node receives permission from the peer node to downtier the data. In response to the permission to downtier the data, the node checks the in progress table for the data and takes an action based on a result of checking the in progress table.

Abstract: Techniques are used for identifying allocated blocks in a storage system. The techniques may be used to provide, among other things, retrieval of a value associated with a most recent reinitialization of the storage system. For a tier of user data storage in the storage system, a page of storage with the value and a marker indicating that the page marks an end of storage that has been allocated for the tier of user data storage may be identified. Storage may be allocated from a page immediately preceding the identified page.

Abstract: A method is used for efficient storage allocation in a storage system. An infrastructure manager receives a request for storage from a first storage operating entity. The infrastructure manager identifies, from entries in a pagebin, a pagelist with sufficient available storage to satisfy the request. The infrastructure manager locks the pagebin while assigning the identified pagelist to the first storage operating entity. Upon a commitment of the identified pagelist by the first storage operating entity, the infrastructure manager unlocks the pagebin and identifies, from the entries in the pagebin, a second pagelist with sufficient available storage to satisfy a request from a second storage operating entity.

Abstract: Techniques are used for identifying allocated blocks in a storage system. The techniques may be used to provide, among other things, retrieval of a value associated with a most recent reinitialization of the storage system. For a tier of user data storage in the storage system, a page of storage with the value and a marker indicating that the page marks an end of storage that has been allocated for the tier of user data storage may be identified. Storage may be allocated from a page immediately preceding the identified page.

Abstract: A method, system, and computer program product for encoded virtual block deferred reference counting comprising receiving an input/output (“IO”) request for data, the data associated with a virtual block, updating a reference count structure to reflect the IO request, and updating, out of line from the IO request, one or more reference counts associated with the virtual block to reflect the result of the IO request based on the updated reference count structure.

Abstract: A method, system, and computer program product for multi-generational virtual block compaction comprising identifying a first virtual block, the first virtual block being associated with a first generation number, determining a second virtual block as an appropriate target for live information in the first virtual block, creating an association between the second virtual block and the first virtual block, updating the live information in the first virtual block to be associated with the second virtual block, updating a generation information mapping associated with the first virtual block; and associating a second generation number with the first virtual block.

Abstract: A method of managing CPU cores in a data storage apparatus (DSA) configured to perform both host I/O (Input/Output) processing and background storage processing is provided. The method includes (a) selectively classifying background storage tasks in one of a first classification for longer-running tasks and a second classification for shorter-running tasks; (b) selecting CPU cores that are running fewer than a threshold number of first-classification background tasks to process host I/O requests; and (c) processing the host I/O requests on their selected CPU cores. An apparatus, system, and computer program product for performing a similar method are also provided.

Abstract: A method is used for efficient storage allocation in a storage system. An infrastructure manager receives a request for storage from a first storage operating entity. The infrastructure manager identifies, from entries in a pagebin, a pagelist with sufficient available storage to satisfy the request. The infrastructure manager locks the pagebin while assigning the identified pagelist to the first storage operating entity. Upon a commitment of the identified pagelist by the first storage operating entity, the infrastructure manager unlocks the pagebin and identifies, from the entries in the pagebin, a second pagelist with sufficient available storage to satisfy a request from a second storage operating entity.

Abstract: A logical unit of non-volatile data storage is provided for persistently storing metadata. The logical unit is provided by allocating RAID (Redundant Array of Independent Disks) extents to the logical unit, and allocating logical block addresses for the logical unit from within a logical address space of the logical unit to store blocks of metadata written to the logical unit. In response to detecting that a stored indication of a last allocated logical block address for the logical unit has been lost, two RAID extents that were last allocated to the logical unit are identified, and a binary search is performed across logical block addresses within the two RAID extents that were last allocated to the logical unit to locate the last allocated logical block address for the logical unit within the logical address space of the logical unit.

Abstract: A logical unit of non-volatile data storage is provided for persistently storing metadata. The logical unit is provided by allocating RAID (Redundant Array of Independent Disks) extents to the logical unit, and allocating logical block addresses for the logical unit from within a logical address space of the logical unit to store blocks of metadata written to the logical unit. In response to detecting that a stored indication of a last allocated logical block address for the logical unit has been lost, two RAID extents that were last allocated to the logical unit are identified, and a binary search is performed across logical block addresses within the two RAID extents that were last allocated to the logical unit to locate the last allocated logical block address for the logical unit within the logical address space of the logical unit.

Abstract: A method, computer program product, and computing system for processing higher-level metadata portions to identify each occurrence of a pointer to a lower-level metadata portion; and generating a pointer record within a memory device that memorializes each occurrence of a pointer to a lower-level metadata portion and identifies a specific lower-level metadata portion to which the pointer is pointing, thus resulting in a plurality of pointer records.

Abstract: A method, computer program product, and computing system for processing higher-level metadata portions to identify each occurrence of a pointer to a lower-level metadata portion; and generating a pointer record within a memory device that memorializes each occurrence of a pointer to a lower-level metadata portion and identifies a specific lower-level metadata portion to which the pointer is pointing, thus resulting in a plurality of pointer records.

Abstract: A method, system, and computer program product for multi-generational virtual block compaction comprising identifying a first virtual block, the first virtual block being associated with a first generation number, determining a second virtual block as an appropriate target for live information in the first virtual block, creating an association between the second virtual block and the first virtual block, updating the live information in the first virtual block to be associated with the second virtual block, updating a generation information mapping associated with the first virtual block; and associating a second generation number with the first virtual block.

Abstract: A method, computer program product, and computer system for forming, by a computing device, one or more virtual storage arrays using one or more storage processor virtual machines. A storage stack may be run inside the one or more storage processor virtual machines. One or more storage device drives of the one or more virtual storage arrays may be simulated as files.

Abstract: A method, system, and computer program product for encoded virtual block deferred reference counting comprising receiving an input/output (“IO”) request for data, the data associated with a virtual block, updating a reference count structure to reflect the IO request, and updating, out of line from the IO request, one or more reference counts associated with the virtual block to reflect the result of the IO request based on the updated reference count structure.

Abstract: A data storage system includes interface circuitry receiving data storage requests and sending corresponding responses to data storage clients, and data storage devices providing non-volatile storing and retrieval of client data in response to the data storage requests. Processing circuitry executes software-implemented datapath modules that realize datapath functions to process the data storage requests and responses, as well as service infrastructure modules to realize a service infrastructure to provide for regularized communications among the datapath modules, including Notify, Monitor, and StartIO communications.

Abstract: Techniques for managing restriping of data across drives of a data storage system in a mapped-RAID environment. In response to addition of a drive to existing drives of the data storage system, all drive extents of the data storage system are mapped out in an effort to consume as much free space as possible across the drives. Having mapped out the drive extents, how many free extents remain on each drive is determined. If a quantity of free extents on a drive exceeds a predetermined threshold number, then that drive is logically marked as requiring restriping. Restriping of data is then performed for all logically marked drives. Once the restriping of the data is completed, a determination is made as to whether any further restriping of data across the drives of the data storage system is required, taking into account a relative wear and/or utilization of the respective physical drives.