Abstract: A data storage system can use non-volatile solid state drives (SSDs) to provide backend storage. The data storage system and SSDs can implement log structured systems (LSSs) experiencing write amplification (WA). The aggregated WA of the LSSs can be minimized when the WAs of both LSSs of the system and SSDs are equal, within a specified tolerance. An amount of storage capacity which the LSS of the data storage system is allowed to use can be limited and vary based on the system's data capacity denoting the storage capacity with valid data. Pm can denote a percentage of Cs, the advertised capacity of the SSDs, storing valid data. Po can be a percentage of Cs denoting the upper bound of the system's used capacity. Po and Pm, as well as the utilization and WA of both the data storage system and SSDs, can be evaluated and adjusted adaptively and holistically.

Abstract: A method may use memory efficiently to extend cache. A processor receives a request to write data. The size of the data in the write request is compared to a threshold. When the size of the data exceeds the threshold, the data is stored on a solid state device. Page descriptors for the data on the solid state device are stored in a metadata log, and a reference to a first page descriptor of the page descriptors in the metadata log is stored in a first hash table in memory.

Abstract: A method, computer program product, and computing system for processing memory page metadata received from a cache memory system within a data storage system to determine if the memory page metadata includes corruption due to a power failure event; if the memory page metadata includes post-acknowledgement data corruption, initiating a data recovery process to attempt to recover content associated with the post-acknowledgement data corruption; and if the memory page metadata includes pre-acknowledgement data corruption, reobtaining content associated with the pre-acknowledgement data corruption.

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 datapath of a data storage system includes receiving a request to access target data and creating a transaction that includes multiple datapath elements in a cache, where the datapath elements are used for accessing the target data. In response to detecting that one of the datapath elements is invalid, the technique further includes processing the transaction in a rescue mode. The rescue mode attempts to replace each invalid datapath element of the transaction with a valid version thereof obtained from elsewhere in the data storage system. The technique further includes committing the transaction as processed in the rescue mode.

Abstract: A data storage system can use non-volatile solid state drives (SSDs) to provide backend storage. The data storage system and SSDs can implement log structured systems (LSSs) experiencing write amplification (WA). The aggregated WA of the LSSs can be minimized when the WAs of both LSSs of the system and SSDs are equal, within a specified tolerance. An amount of storage capacity which the LSS of the data storage system is allowed to use can be limited and vary based on the system’s data capacity denoting the storage capacity with valid data. Pm can denote a percentage of Cs, the advertised capacity of the SSDs, storing valid data. Po can be a percentage of Cs denoting the upper bound of the system’s used capacity. Po and Pm, as well as the utilization and WA of both the data storage system and SSDs, can be evaluated and adjusted adaptively and holistically.

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: A method, computer program product, and computer system for submitting, by a computing device, a write for a write-request equal to a size of valid data in a segment. The write-request may be decomposed into RAID elements and corresponding parity stripe elements. Parity for RAID stripes may be calculated using only valid RAID elements of the RAID elements. A write for all the valid RAID elements and the corresponding parity stripe elements may be issued. An unmap command may be issued to at least a portion of the segment that is invalid.

Abstract: Techniques for rebuilding data in a data storage system are provided. A method includes: (a) identifying (i) a first set of degraded Ubers that contain no portions reserved for direct writing and (ii) a second set of degraded Ubers that contain at least one portion reserved for direct writing. Direct writing is a process that writes blocks to long-term storage prior to mapping those blocks in a metadata mapping structure. An Uber is a set of adjacent stripes across a respective Redundant Array of Independent Disks (RAID) array of the data storage system, and a degraded Uber is an Uber that includes at least one failed drive within its RAID array. The method further includes (b) initiating a rebuild of the first set of degraded Ubers; and (c) delaying a rebuild of each degraded Uber of the second set until all pending direct writes to blocks of that degraded Uber have been mapped by the metadata mapping structure.

Abstract: A method of validating metadata pages that map to user data in a data storage system is provided. The method includes (a) obtaining first information stored for a first metadata page and second information stored for a second metadata page, the first and second metadata pages having a relationship to each other within a hierarchy of metadata pages for accessing user data; (b) performing a consistency check between the first information and the second information, the consistency check producing a first result in response to the relationship being verified and a second result otherwise; and (c) in response to the consistency check yielding the second result, performing a corrective action to restore consistency between the first and second information. An apparatus, system, and computer program product for performing a similar method are also provided.

Abstract: A method, computer program product, and computing system for receiving a plurality of input/output (IO) requests at a storage system. One or more IO properties may be extracted from the plurality of IO requests. The one or more IO properties may be processed, using one or more machine learning models, to define an access temperature value for one or more storage objects of the storage system. The one or more storage objects may be tiered between a plurality of storage tiers of the storage system, based upon, at least in part, the access temperature values defined for the one or more storage objects of the storage system and one or more tiering policies.

Abstract: A method, computer program product, and computing system for allocating a first number of tokens from a plurality of tokens for processing read IO requests from a read IO queue, thus defining a number of allocated read tokens. A second number of tokens may be allocated from the plurality of tokens for processing write IO requests from a write IO queue, thus defining a number of allocated write tokens. It may be determined that the processing of the write IO requests is throttled. In response to determining that the processing of the write IO requests from the write IO queue is throttled, a maximum allowable number of write tokens may be defined. Additional tokens may be allocated for processing the read IO requests from the read IO queue based upon, at least in part, the maximum allowable number of write tokens and the number of allocated write tokens.

Abstract: A method, computer program product, and computer system for receiving, by a computing device, a snapshot create operation of a volume to create a first snapshot. Existing dirty data of the volume for the first snapshot may be flushed from an in-memory cache. New writes to the volume for the first snapshot may be maintained in the in-memory cache as dirty. A snapshot create operation to the volume may be received to create a second snapshot. The new writes to the volume for the first snapshot may be combined as part of the second snapshot.

Abstract: A method, computer program product, and computer system for identifying, by a computing device, a number of extents needed for a create snapshot operation to create a snapshot. The number of extents may be added to an in-memory cache. The number of extents needed for the create snapshot operation may be allocated from the in-memory cache to execute the create snapshot operation. Freed extents may be added to the in-memory cache based upon, at least in part, executing a delete snapshot operation to delete the snapshot.

Abstract: A method, computer program product, and computer system for receiving, by a computing device, a plurality of IO requests. A portion of the plurality of IO requests may be aggregated based upon a block size. The portion of the plurality of IO requests may be committed to persistent storage in a batch based upon, at least in part, aggregating the portion of the plurality of IO requests based upon the block size.

Abstract: A method, computer program product, and computer system for receiving an XCopy command is provided. The XCopy command may be in the form of an IO operation. The IO operation may be a subextent block operation. A source range and a destination range of the XCopy command may be determined to be aligned within an alignment boundary. The Xcopy command may be determined to be smaller than a predetermined size. In response to determining the source range and destination range of the XCopy command are aligned within the alignment boundary and the XCopy command is smaller than a predetermined size, the XCopy command may be processed. The receiving of the XCopy command may be recorded in a log.

Abstract: A method, computer program product, and computing system for maintaining a first cursor pointer for a memory system, wherein the first cursor pointer concerns a first search criteria and identifies an initial first cursor starting location; receiving a first search request for the memory system that satisfies the first search criteria; executing the first search request within an initial first search window starting at the initial first cursor starting location; and updating the first cursor pointer to identify an updated first cursor starting location based, at least in part, upon the initial first search window.

Abstract: A technique provides preferential treatment to metadata over user data when protecting data in a mapped-RAID system. The technique involves generating metadata based on user data, storing the metadata in mirrored storage of the mapped-RAID system (e.g., 2-way mirrored storage), and storing the user data in non-mirrored storage of the mapped-RAID system (e.g., writing user data with parity in accordance with RAID 6). The mapped-RAID system provides reliability preference toward maintaining the metadata over maintaining the user data while the metadata and the user data are stored within the mapped-RAID system. Accordingly, the technique is able to concurrently provide high reliability and high storage efficiency.

Abstract: A technique manages data within a storage array. The technique involves forming a hybrid tier within the storage array, the hybrid tier including SSD storage and HDD storage. The technique further involves, after the hybrid tier is formed, providing hybrid ubers (or Redundant Array of Independent Disks (RAID) extents) from the SSD storage and the HDD storage of the hybrid tier. The technique further involves, after the hybrid ubers are provided, accessing the hybrid ubers to perform data storage operations.