Abstract: In a multi-tiered system, a read temperature classification and write temperature classification per virtual block (VLB) can be determined based on the content referenced by each VLB. The temperature classifications of VLBs can be determined using temperature scales which map read and write activity levels to corresponding temperature classifications. The temperature scales can have classification boundaries adjusted based on feedback of operations performed including down-tiering, garbage collection, and compaction and appending. In one use case, a number of free blocks in a high-performance first tier can be below a minimum and processing can be performed to locate a source block of the first tier partially filled with hot content, store the hot content contiguously on a target block of the first tier, flush write data from a log, and store the write data on the target block by appending the write data to the existing hot content.

Abstract: A technique for performing data deduplication operates at sub-block granularity by searching a deduplication database for a match between a candidate sub-block of a candidate block and a target sub-block of a previously-stored target block. When a match is found, the technique identifies a duplicate range shared between the candidate block and the target block and effects persistent storage of the duplicate range by configuring mapping metadata of the candidate block so that it points to the duplicate range in the target block.

Abstract: In a multi-tiered system, read temperature and write temperature per virtual block (VLB) can be determined based on the content referenced by each VLB. The read temperature can describe VLB read activity relative to the recency and frequency of read misses of content referenced by the VLB. The write temperature can describe VLB write activity relative to the recency and frequency of overwrites with respect to content referenced by the VLB. Read misses and overwrites can be recorded per processing core in an active tablet used for recording by only a single core. Active and analytic tablet sets across cores can be switched based on criteria. Analytic tablets can be processed and used to update metrics, including read and write temperatures, stored for VLBs. The metrics can be used to determine temperature classifications of VLBs. Content referenced by VLBs can be promoted and/or demoted using VLB temperature classifications.

Abstract: Techniques for providing multi-tier heat maps in a storage system. The techniques include obtaining a temperature of a storage object using a first heat map of data IO activity at a storage object level of the data, and determining that the temperature of the storage object exceeds a predetermined threshold. The techniques further include, in response to determining that the temperature of the storage object exceeds the predetermined threshold, obtaining at least one temperature of at least one storage element associated with the storage object using a second heat map of data IO activity at a storage element level of the data, and performing a storage operation on the storage object based on the temperature of the storage object and/or the temperature of the storage element. Such use of multi-tier heat maps allow accurate temperature predictions to be made in a manner that conserves and adapts to available system resources.

Abstract: Techniques for providing effective utilization of different drive capacities in storage appliances. The techniques include providing a storage drive array that has a first set of storage drives and a second set of storage drives. Each storage drive in the first set has a first drive capacity and each storage drive in the second set has a second drive capacity. The first drive capacity is higher than the second drive capacity. The techniques include allocating, within the first drive capacity, at least a first sub-capacity and a second sub-capacity. The first sub-capacity is equal to the second drive capacity. The techniques include placing blocks of hot data in the first sub-capacities of the storage drives in the first set and/or the second drive capacities of the storage drives in the second set, and placing blocks of cold data in the second sub-capacities of the storage drives in the first set.

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: Processing can be performed to persistently record, in a log, a write I/O that writes first data to a target logical address. The processing can include: allocating storage for a first page buffer (PB) located at offsets in a PB pool of non-volatile storage of the log; enqueuing a request to an aggregation queue to persistently store the first data to the first PB of the log, wherein the request identifies the offsets of the PB pool of non-volatile storage which correspond to the first PB; and integrating the request into the aggregation queue. Integrating can include: determining whether a contiguous segment of the offsets of the request is adjacent to a second contiguous segment of the aggregation queue; and responsive to determining the contiguous segment is adjacent to the second contiguous segment, merging the first and second contiguous segments and generating an aggregated continuous segment.

Abstract: A data storage system includes a tuner that obtains data samples for data storage operations of workloads and calculates feature measures for a set of features of the data storage operations over aggregation intervals of an operating period. It further (1) applies a cluster analysis to the feature measures to define a set of clusters, and assigns the feature measures to the clusters, and (2) applies a classification analysis to the feature measures labelled by their clusters to identify dominating features of each cluster, and generates workload profiles for the clusters based on the dominating features, and then automatically adjusts configurable processing mechanisms (e.g., caching or tiering) based on the workload profiles and performance or efficiency goals.

Abstract: A technique is directed to providing dynamic redundant array of independent disks (RAID) transformation which involves measuring a set of storage array parameters for an existing RAID configuration residing in a storage array. The technique further involves identifying a new RAID configuration to use in place of the existing RAID configuration based on the measured set of storage array parameters. The technique further involves, after the new RAID configuration is identified, transforming the existing RAID configuration into the new RAID configuration.

Abstract: A technique for copying data from a source range to a destination range includes identifying a chunk of the source range. The chunk includes multiple logical blocks that map, through a series of source-mapping pages, to a set of virtual pages that point to physical data of the chunk. The technique further includes copying the series of source-mapping pages to form a corresponding series of destination-mapping pages pointed to by the destination range, so that a corresponding chunk of the destination range maps, via the series of destination-mapping pages, to the same set of virtual pages mapped to by the series of source mapping pages.

Abstract: Processing can be performed to persistently record, in a log, a write I/O that writes first data to a target logical address. The processing can include: allocating storage for a first page buffer (PB) located at offsets in a PB pool of non-volatile storage of the log; enqueuing a request to an aggregation queue to persistently store the first data to the first PB of the log, wherein the request identifies the offsets of the PB pool of non-volatile storage which correspond to the first PB; and integrating the request into the aggregation queue. Integrating can include: determining whether a contiguous segment of the offsets of the request is adjacent to a second contiguous segment of the aggregation queue; and responsive to determining the contiguous segment is adjacent to the second contiguous segment, merging the first and second contiguous segments and generating an aggregated continuous segment.

Abstract: Data replication techniques can include receiving, at a source system, a write directed to a source logical device configured for asynchronous remote replication to a destination system; performing processing that flushes a transaction log entry for the write; and performing replication processing that uses a replication queue including a replication queue entry corresponding to the write that stores the first content to a logical address. The processing can create a replication log entry in a replication log for the write responsive to determining that the write is directed to the source logical device configured for asynchronous remote replication and that the first content has not been replicated. Responsive to the first content not being in cache, the first content can be retrieved using the reference to a storage location storing the first content. The reference can be obtained from the replication log entry or the replication queue entry.

Abstract: Techniques for forecasting temperatures of storage objects in a storage system using machine learning (ML). The techniques can include forecasting at least one temperature of a storage object using at least one ML model, modifying storage of the storage object based on the at least one temperature of the storage object, and, having modified storage of the storage object, obtaining at least one performance metric associated with the storage object. The techniques can further include, based on the performance metric(s), varying a frequency of forecasting the at least one temperature of the storage object, retraining the at least one ML model used in forecasting the at least one temperature, and/or adjusting at least one operational parameter of the system. The techniques provide increased accuracy over known statistical approaches to forecasting temperatures of storage objects, leading to increased performance gains in terms of IO latency, IO operations per second, and bandwidth.

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: Techniques for managing storage may comprise: receiving a request for a first amount of free capacity, wherein the request includes a first priority denoting a purpose for which the first amount of free capacity is requested; determining whether a current utilization of storage exceeds a first threshold associated with the first priority; responsive to determining the current utilization of storage is less than the first threshold associated with the first priority, performing first processing including: determining whether there is a sufficient amount of existing free capacity to grant the first amount; and responsive to determining there is a sufficient amount of existing free capacity to grant the first amount, granting the first amount of free capacity; and responsive to determining the current utilization of storage is not less than the first threshold associated with the first priority, rejecting the request and not granting the first amount of free capacity.

Abstract: In a log based system, a reclamation list of cache pages containing dirty data can be maintained and used. The cached dirty data pages identified by the reclamation list can be candidates for eviction from the cache. A cached dirty data page on the reclamation list can be persistently logged in a transaction log extension having storage allocated from a non-volatile solid state drive (SSD). The reclamation list can include descriptors of the cached dirty data pages prioritized for eviction in accordance with a least recently used (LRU) policy so that the LRU cached dirty data page can be selected for eviction. When a dirty data page which was evicted from the cache is reloaded into cache, the dirty data page can be added to the reclamation list by adding its page descriptor to the reclamation list. A dirty data page can be removed from the reclamation list once flushed.

Abstract: Data replication techniques can include receiving, at a source system, a write directed to a source logical device configured for asynchronous remote replication to a destination system; performing processing that flushes a transaction log entry for the write; and performing replication processing that uses a replication queue including a replication queue entry corresponding to the write that stores the first content to a logical address. The processing can create a replication log entry in a replication log for the write responsive to determining that the write is directed to the source logical device configured for asynchronous remote replication and that the first content has not been replicated. Responsive to the first content not being in cache, the first content can be retrieved using the reference to a storage location storing the first content. The reference can be obtained from the replication log entry or the replication queue entry.

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: In a log based system, a reclamation list of cache pages containing dirty data can be maintained and used. The cached dirty data pages identified by the reclamation list can be candidates for eviction from the cache. A cached dirty data page on the reclamation list can be persistently logged in a transaction log extension having storage allocated from a non-volatile solid state drive (SSD). The reclamation list can include descriptors of the cached dirty data pages prioritized for eviction in accordance with a least recently used (LRU) policy so that the LRU cached dirty data page can be selected for eviction. When a dirty data page which was evicted from the cache is reloaded into cache, the dirty data page can be added to the reclamation list by adding its page descriptor to the reclamation list. A dirty data page can be removed from the reclamation list once flushed.

Abstract: A method, computer program product, and computing system for identifying a first memory device source that includes first content; identifying a second memory device source that include second content; and initiating a first iteration of a memory device cleansing procedure wherein first content and at least a first portion of the second content are moved to a first unused memory device.