Abstract: A method for use in a storage node, the method comprising: instantiating a first poller for detecting whether pending storage device operations have been completed; executing the first poller to identify a first storage device operation that has been completed, wherein executing the first poller includes: (a) executing a first function to detect whether a completion queue corresponding to a storage device driver is empty, the first function being arranged to read a content of a memory location that is associated with the completion queue, (b) terminating the execution of the first poller when the completion queue is empty, and (c) executing a system call function to the storage device driver when the completion queue is non-empty; identifying a first thread that is waiting for the first storage device operation to be completed; and transitioning the first thread from a waiting state to a ready state.

Abstract: A method, computer program product, and computer system for receiving, by a computing device, an IO request on a first node. It may be determined whether a virtual address for the IO request is in a virtual cache. A read to RAID may be issued using the virtual address when the virtual address for the IO request is not in the virtual cache. A return of a cached page associated with the virtual address may be issued when the virtual address for the IO request is in the virtual cache.

Abstract: A processing device is configured to obtain an input-output operation that corresponds to a first metadata page and to identify a corresponding binary tree. The binary tree comprises a plurality of nodes each comprising a delta corresponding to a metadata page. The processing device is further configured to perform a read traversal process corresponding to the first metadata page which comprises traversing the binary tree based at least in part on the first metadata page while the binary tree is locked by a node insertion process corresponding to a second metadata page. The node insertion process comprises inserting a first node corresponding to the second metadata page into the binary tree. The read traversal process further comprises locating a second node of the binary tree that corresponds to the first metadata page and obtaining a first delta that corresponds to the first metadata page from the second node.

Abstract: A mapper tree for a logical volume is provided by storing, in each leaf node of the mapper tree, pointers to pages of non-volatile storage that store host data written to corresponding pages within a segment of the logical address space of the logical volume that corresponds to the leaf node. In response to receiving an initial write operation directed to a segment of the logical address space of the logical volume for which no leaf node currently exists in the mapper tree, a representation of a new leaf node is added to a super leaf node in the mapper tree that efficiently stores representations of multiple leaf nodes.

Abstract: A method, computer program product, and computing system for associating each data container of a first set of data containers in volatile memory with a metadata page. One or more metadata changes associated with a metadata page may be written to the data container associated with the metadata page. The one or more metadata changes stored in the first set of data containers may be written to a storage array.

Abstract: Techniques for processing operations may include: receiving, at a data storage system from a host, an operation requesting to perform an offload copy operation internally within the data storage system, wherein the operation indicates that the offload copy operation copies data from a source interval to a destination interval; inserting a record in a log file logging the offload copy operation; inserting a source node representing the source interval in a source interval tree, wherein each node in the source interval tree represents a source interval of an offload copy operation having a corresponding record in the log file; inserting a destination node representing the destination interval in a destination interval tree, wherein each node in the destination interval tree represents a destination interval of an offload copy operation having a corresponding record in the log file; and returning an acknowledgement to the host regarding the offload copy operation.

Abstract: Techniques for optimizing write IO bandwidth and latency in an active-active clustered system using storage object affinity to a single node. The active-active clustered system can include at least a primary storage node and a secondary storage node that maintain their own journals. The respective journals are directly accessible to both storage nodes. The journals are synchronized for each page or entity of a storage object when a storage IO request is issued to a storage node to which the storage object does not have affinity. Such synchronization is performed in the framework of acquiring a lock on the entity of the storage object during internode communications. To facilitate recovery from a disaster, data loss, and/or data corruption, transaction IDs associated with storage IO operations are employed to facilitate identification of the most up-to-date reference or description information for a given data or metadata page of a storage object.

Abstract: An aspect of performance optimization in a storage system environment includes providing a metadata structure that describes a storage space of a storage system. For each storage object of a plurality of storage objects, an aspect includes monitoring input/output (IO) patterns for IO operations conducted, monitoring deduplication characteristics of the storage object, and configuring local mapping layer parameters. An aspect further includes modifying local object metadata in the metadata structure as a function of the monitoring and the configuring.

Abstract: A technique for performing deduplication identifies representative sub-blocks within candidate blocks and performs sub-block matching to entries in a digest database. When a representative sub-block is matched to a differently-aligned target sub-block that belongs to a target block, the technique effectuates storage of the candidate block using the target block and a block adjacent to the target block.

Abstract: A technique is directed to managing a redundant array of independent disks (RAID) group. The technique involves forming the RAID group from storage devices of different types that provide different data storage characteristics. The technique further involves receiving input/output (I/O) requests, and performing I/O operations on the RAID group in response to the I/O requests.

Abstract: Virtual block redirection clean-up is accomplished for a virtual block in a mapper tree for a logical volume that is redirected to a destination virtual block in the mapper tree. In response to redirection of the virtual block, a redirection notification is sent to each component in a set of dependent components. Each dependent component may store one or more pointers to pointers located within virtual blocks of the mapper tree. The redirected virtual block is cleaned up in response to determining that each dependent component has expressly indicated, in response to the redirection notification, that it does not store any pointer to any pointer that is located within the redirected virtual block.

Abstract: Techniques for providing metadata (and/or data) protection in a data storage system. The techniques can include storing, for a specific data page, two (2) instances of a main metadata page and one (1) instance of a corresponding alternative metadata page in a protected storage object referred to herein as the “2+1-way mirror”. For the specific data page, two (2) instances of a main metadata page can be stored on a first drive and a second drive, respectively, of the 2+1-way mirror such that the first and second drives each have a copy of the same main metadata page. Further, an instance of a corresponding alternative metadata page can be stored on a third drive of the 2+1-way mirror. The 2+1-way mirror provides protection against metadata loss due to the concurrent failure of two (2) physical drives, and further provides protection against catastrophic metadata errors and/or inconsistencies due to software failures.

Abstract: A technique for performing deduplication identifies representative sub-blocks within candidate blocks and performs sub-block matching to entries in a digest database. When a representative sub-block is matched to a differently-aligned target sub-block that belongs to a target block, the technique effectuates storage of the candidate block using the target block and a block adjacent to the target block.

Abstract: A technique for performing deduplication traverses a deduplication database and assigns digest values in the database to buckets, where each bucket covers a respective range of digest values. To deduplicate a particular candidate block, the technique generates a digest from the candidate block and searches for the computed digest in a subset of the buckets, where the subset is selected based on the computed digest. If a target block providing an exact match or a suitably close partial match is found in the subset of buckets, the technique effects storage of the candidate block at least in part by providing a reference to the target block.

Abstract: A technique for managing deduplication performs partial-block matching opportunistically by leveraging information acquired during times when a storage system has available resources. The information identifies anchor blocks that are likely targets for partial-block matches, based on discovering that the anchor blocks belong to populations of blocks that have high similarity. When processing write requests, inline activities access anchor blocks that closely match newly arriving candidate blocks and perform partial-block deduplication against those anchor blocks.

Abstract: A method, computer program product, and computer system for receiving, by a computing device, an IO request on a first node. It may be determined whether a virtual address for the IO request is in a virtual cache. A read to RAID may be issued using the virtual address when the virtual address for the IO request is not in the virtual cache. A return of a cached page associated with the virtual address may be issued when the virtual address for the IO request is in the virtual cache.

Abstract: A technique for performing deduplication extends a match found in a digest database by looking forward and/or backward to adjacent data elements. The technique performs data comparisons between data blocks adjacent to a candidate block and corresponding data blocks adjacent to an identified target block. If the data comparisons indicate that an adjacent candidate block matches an adjacent target block, then the adjacent candidate block may be deduplicated to the adjacent target block without having to compute a hash value of the adjacent candidate block or to perform a separate lookup into the digest database.

Abstract: Techniques for data processing may include: receiving a page P having a binary representation; determining a plurality of features for the page P; determining a plurality of feature hashes for the plurality of features, wherein each of the plurality of feature hashes corresponds to a different one of the plurality of features, wherein said each feature hash is determined using a hash function and in accordance with said different one of the plurality of features and an index associated with said different one of the plurality of features; and determining, in accordance with the plurality of feature hashes for the plurality of features, a similarity hash for the page P.

Abstract: Techniques for determining unique ownership of data blocks includes selecting a first data block referenced by a first logical address of a first logical device, wherein first metadata for the first data block includes a reference count and a result used in determining sole unique ownership of the first data block; determining C1, an expected value of the result of the first metadata when the first logical device is a sole unique owner of the first data block; and performing first processing that determines whether the first logical device is the sole unique owner of the first data block. The first processing includes: determining whether C1 equals a current value of the result of the first metadata; and determining that the first logical device is the sole unique owner of the first data block if C1 equals the current value of the result of the first metadata.

Abstract: A storage system comprises multiple storage nodes each comprising at least one storage device. Each of the storage nodes further comprises a set of processing modules configured to communicate over one or more networks with corresponding sets of processing modules on other ones of the storage nodes. The sets of processing modules of the storage nodes each comprise at least one data module and at least one control module. The storage system is configured to assign portions of a content-based signature space of the storage system to respective ones of the data modules, and to assign portions of a logical address space of the storage system to respective ones of the control modules. The assignment of portions of the logical address space to the control modules is configured to at least partially offset an unbalanced condition between local physical storage capacities of the data modules.