Abstract: Techniques for processing data may include: receiving a data block stored in a data set, wherein a hash value is derived from the data block; determining, in accordance with selection criteria, whether the hash value is included in a subset; responsive to determining the hash value is included in the subset, performing processing that updates a table in accordance with the hash value and the data set, and determining, in accordance with the information in the table, whether to perform deduplication processing for the data block to determine whether the data block is a duplicate of another stored data block. The table may include an entry for the hash value. The entry may include information identifying data sets referencing the data block and, for each of the data sets, may specify a reference count denoting a number of times the data set references the data block.

Abstract: A method may select a surviving storage node based on environmental conditions. A request for exclusive access to a volume is received. A score based on data associated with an environment of the node is determined for each node in a cluster. Based on the scores, a node to grant exclusive access to the volume is identified, and such exclusive access is granted to the identified node.

Abstract: In a protective quorum service, during an initial period of normal operation in which a clustered pair of data storage nodes provide host I/O access to a data storage object and replicate write-type requests to each other, the nodes are first registered to the quorum service. Subsequently, based on the registration and in response to a first auto promote request from a first-requesting node, a success response is returned and the service enters an auto promoted condition, the success response indicating that the first-requesting node is to continue providing the host I/O access to the data storage object without write replication. In response to receiving a subsequent auto promote request from the other node when in the auto promoted condition, a failure response is returned indicating that the other node is to cease providing host I/O access to the data storage object.

Abstract: A stretched volume may be configured from N volumes of N data storage systems configured as a cluster. N may be an integer greater than two. Each of the N volumes may be included in a different one of the N data storage systems. The N volumes may be exposed to a host as a logical volume having a unique identifier over a plurality of paths from the N data storage systems. The N volumes may be configured for multidirectional synchronous replication. At a first system of the cluster, a write operation may be received that writes to a target logical address of the stretched volume. Servicing the first write may include synchronously replicating the first write to every other one of the N data storage systems of the cluster. Also described are techniques for handling lock contention and avoiding deadlock in connection with processing writes to the stretched volume.

Abstract: An apparatus comprises at least one processing device that includes a processor coupled to a memory. The processing device is configured to identify a plurality of resource objects associated with a processing device, to group correlated resource objects according to processing device utilization of the resource objects, to assign a first weight to a first resource object grouping, wherein the first weight is associated with a performance impact of the first resource object grouping on the processing device, and to release at least some of the first resource object grouping to provide additional resources to a second resource object grouping, the additional resources resulting from the releasing, wherein the first object grouping is selected for the releasing based on a comparison between the first weight and a second weight associated with the second resource object grouping, wherein the releasing is performed to improve performance of the processing device.

Abstract: An apparatus comprises at least one processing device that includes a processor coupled to a memory. The processing device is configured to receive, by a trace filter system, a trace chunk from a trace buffer associated with a processor core in a processing device, where the trace buffer is comprised of a plurality of trace chunks, to filter, by the trace filter system, the trace chunk, and to store the filtered trace chunk in the trace buffer.

Abstract: A method, computer program product, and computing system for dividing a plurality of volumes replicated across a pair of storage systems into one or more consistency groups. A polarization state may be defined for each consistency group. An input-output (IO) failure associated with at least one consistency group may be detected. At least a portion of the at least one consistency group may be polarized based upon, at least in part, the polarization state defined for the at least one consistency group.

Abstract: A technique for maintaining synchronization between two arrays includes assigning one array to be a preferred array and the other array to be a non-preferred array. When write requests are received at the preferred array, the writes are applied locally first and then applied remotely. However, when write requests are received at the non-preferred array, such writes are applied remotely first and then applied locally. Thus, writes are applied first on the preferred array and then on the non-preferred array, regardless of whether the writes are initially received at the preferred array or the non-preferred array.

Abstract: A storage system comprises a plurality of storage nodes each comprising one or more storage devices and a processor coupled to a memory. The storage system is configured to store data blocks across the storage devices of the storage nodes utilizing a redundant array of independent disks (RAID) arrangement. At least a given one of the storage nodes is configured to store a plurality of RAID metadata bitmaps in persistent storage of the storage node so as to be available for a recovery operation in the event of a detected failure, to identify a particular subset of the RAID metadata bitmaps to be updated in conjunction with an additional operation other than the recovery operation, and to temporarily store the identified subset of the RAID metadata bitmaps in the memory of the storage node in a manner determined based at least in part on an operation type of the additional operation.

Abstract: An apparatus in one embodiment includes at least one processing device comprising a processor coupled to a memory, with the at least one processing device being configured to maintain a replication journal for recording replication write requests in a storage system, to detect a failure impacting the replication journal, and to initiate recovery of the replication journal responsive to the detected failure. In conjunction with the recovery of the replication journal, the at least one processing device is further configured to maintain a lock contention table that characterizes lock contentions between address lock ranges required for the recovery of the replication journal and address lock ranges required by other write requests in the storage system, and to utilize the lock contention table to resolve one or more potential deadlocks that would otherwise prevent completion of the recovery of the replication journal. Other embodiments include methods and computer program products.

Abstract: In one aspect, an example methodology implementing the disclosed techniques includes creating, by a first site of a volume that supports active-active bidirectional replication, a local copy of the volume, the local copy of the volume configured to be active. The method also includes enabling, by the first site of the volume, bidirectional write input/output (I/O) mirroring with a second site of the volume. The method further includes, by the second site of the volume, creating a remote copy of the volume, the remote copy of the volume configured to be passive, and enabling bidirectional write I/O mirroring with the first site of the volume.

Abstract: A method, computer program product, and computing system for dividing a plurality of volumes replicated across a pair of storage systems into one or more consistency groups. A polarization state may be defined for each consistency group. An input-output (IO) failure associated with at least one consistency group may be detected. At least a portion of the at least one consistency group may be polarized based upon, at least in part, the polarization state defined for the at least one consistency group.

Abstract: In a protective quorum service, during an initial period of normal operation in which a clustered pair of data storage nodes provide host I/O access to a data storage object and replicate write-type requests to each other, the nodes are first registered to the quorum service. Subsequently, based on the registration and in response to a first auto promote request from a first-requesting node, a success response is returned and the service enters an auto promoted condition, the success response indicating that the first-requesting node is to continue providing the host I/O access to the data storage object without write replication. In response to receiving a subsequent auto promote request from the other node when in the auto promoted condition, a failure response is returned indicating that the other node is to cease providing host I/O access to the data storage object.

Abstract: A method, computer program product, and computing system for receiving, at a cache memory system, a write request for writing data to a storage system. A data reduction rate may be predicted for the write request. One or more portions of memory within the storage system may be allocated based upon, at least in part, the predicted data reduction rate for the write request. The write request may be flushed from the cache memory system to the allocated one or more portions of memory within the storage system.

Abstract: A method is used in issuing alerts for storage volumes using machine learning. A machine learning system analyzes Input/Output (I/O) data of a storage volume in a data storage system. The machine learning system is trained with sample I/O data patterns associated with the storage volume. Based on the I/O data, the machine learning system identifies atypical behavior associated with I/O data patterns of the I/O data. The method then issues an alert.

Abstract: A method is used in issuing alerts for storage volumes using machine learning. A machine learning system analyzes Input/Output (I/O) data of a storage volume in a data storage system. The machine learning system is trained with sample I/O data patterns associated with the storage volume. Based on the I/O data, the machine learning system identifies atypical behavior associated with I/O data patterns of the I/O data. The method then issues an alert.

Abstract: For each of multiple storage volumes of a distributed storage system, it is determined whether the storage volume has a relatively high potential deduplicability or a relatively low potential deduplicability. Responsive to determining that the storage volume has the relatively high potential deduplicability, a first write flow is executed for each of a plurality of write requests directed to the storage volume, the first write flow utilizing content-based signatures of respective data pages of the storage volume to store the data pages in storage devices of the distributed storage system. Responsive to determining that the storage volume has the relatively low potential deduplicability, a second write flow is executed for each of a plurality of write requests directed to the storage volume, the second write flow utilizing non-content-based signatures of respective data pages of the storage volume to store the data pages in storage devices of the distributed storage system.

Abstract: An aspect of performing rollback of a snapshot between source and target storage systems in an asynchronous replication session in which Sr? represents a remote snapshot subject to the rollback includes suspending host input/output operations to a current source volume (Vs), determining whether a snapshot (Sr) matching the snapshot Sr? is present in the source system and, upon determining the snapshot Sr is not present in the source storage system, searching a snapshot pair (Sk, Sk?) that is closest to the remote snapshot Sr?. An aspect also includes upon determining the pair Sk, Sk? is present in existing snapsets, performing a local rollback of the Vs to Sk, and performing remote rollback including applying a difference between Sk? and Sr? to the Vs via one of a snapshot differential bitmap from the target storage system between Sk? and Sr? for the Vs, and an internal reverse direction asynchronous replication cycle.

Abstract: Host I/O requests directed to a logical storage volume are initially processed by accessing physical pages of non-volatile data storage having a default page size. An indication of an optimal page size for the logical storage volume is received, and the size of the physical pages of non-volatile data storage accessed to process host I/O requests directed to the logical storage volume is changed from the default page size to the optimal page size for the logical storage volume. The default page size is changed to the optimal page size for the logical storage volume by changing a size of physical pages of non-volatile data storage indicated by a mapping structure that maps logical addresses in an address space the logical storage volume to corresponding physical pages of non-volatile data storage from the default page size to the optimal page size for the logical storage volume.

Abstract: A storage system in one embodiment 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 control module. The storage system is configured to assign portions of a logical address space of the storage system to respective ones of the control modules, to receive a plurality of tracks of data records in a count-key-data format, and to store the tracks in respective ones of the portions of the logical address space assigned to respective ones of the control modules. Each of the tracks is stored in its entirety in the portion of the logical address space assigned to a corresponding one of the control modules.