Abstract: A data storage system performs updating of a set of global counters stored in persistent storage accessible to a plurality of processing nodes of a data storage system, the global counters storing respective global count values describing associated units of data storage shared by the processing nodes for performing data storage operations. The updating includes, by each processing node, using a respective set of in-memory delta counters storing respective delta count values to track changes to respective global count values due to data storage operations performed by the processing node with respect to the units of data storage. A summarization process is regularly executed to merge the delta count values of the delta counters of all processing nodes into the respective global counters.

Abstract: A technique for managing data received into a cache operates in cycles. To process a current batch of compressed blocks during a current cache processing cycle, a storage system obtains a new mapping structure and a new segment of contiguous storage space. If the system can place some of the current batch of compressed blocks into previously-allocated space, the system does so and partially populates the new mapping structure with entries for mapping the other compressed blocks that were not placed. The system then asserts a hold on the new mapping structure, so that the mapping structure is retained in cache at the end of the current cache processing cycle, and more completely populates the new mapping structure with entries for other compressed blocks during a later cache processing cycle before releasing the hold.

Abstract: There is disclosed techniques for use in managing data storage in storage systems. For example, in one embodiment, there is disclosed a method comprising receiving a request to store data of a data object in a storage system. The method also comprising determining that at least a portion of the data is to be stored in an uncompressed format in the storage system in response to receiving the request. The method also comprising storing at least a portion of the data in the uncompressed format in an allocation unit of a segment in the storage system such that the stored data in the uncompressed format emulates stored data in a compressed format based on the said determination.

Abstract: A technique for managing a metadata transaction log consolidates multiple mapping pointer changes that affect a single metadata block in a single transaction entry. The technique creates a data structure that identifies the mapping pointers in the metadata block that are changing, and stores the data structure in the transaction entry along with records that describe the individual mapping pointer changes.

Abstract: A technique for managing data received into a cache operates in cycles. To process a current batch of compressed blocks during a current cache processing cycle, a storage system obtains a new mapping structure and a new segment of contiguous storage space. If the system can place some of the current batch of compressed blocks into previously-allocated space, the system does so and partially populates the new mapping structure with entries for mapping the other compressed blocks that were not placed. The system then asserts a hold on the new mapping structure, so that the mapping structure is retained in cache at the end of the current cache processing cycle, and more completely populates the new mapping structure with entries for other compressed blocks during a later cache processing cycle before releasing the hold.

Abstract: A method is used in managing deduplication characteristics in a storage system. Deduplication entries stored in a deduplication cache are categorized into a set of deduplication groups based on a data deduplication probability associated with the deduplication entries. A machine learning system is used to dynamically adjust deduplication characteristics associated with the set of deduplication groups based on an I/O workload associated with the storage system.

Abstract: A technique for writing data in a file system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs an FS-relocate operation by accessing an F S-hole list provided for the file system and selecting a hole, from the FS-relocate list, which is large enough to accommodate the compressed extent. The technique then places the compressed extent in the selected hole.

Abstract: A technique for writing data in a data storage system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs a batch-relocate operation by gathering a set of mapping metadata for mapping each of the extents in the batch, identifying a set of holes indicated by the set of mapping metadata, and adding the holes to a batch-hole list. The technique then selects a hole, from the batch-hole list, which is big enough to accommodate the compressed extent, and places the compressed extent in the selected hole.

Abstract: A technique for managing storage of compressed data includes generating and enforcing a minimum slot size requirement. The minimum slot size is based at least in part on collected performance metrics that indicate a degree of compressibility of data received, compressed, and written by the data storage system. As new data arrive, the new data are compressed and stored in slots at least as big as the minimum slot size, in many cases effecting an over-allocation of storage space and improving the likelihood that subsequent overwrites will fit into existing slots.

Abstract: A method is used in managing deduplication characteristics in a storage system. Deduplication entries stored in a deduplication cache are categorized into a set of deduplication groups based on a data deduplication probability associated with the deduplication entries. A machine learning system is used to dynamically adjust deduplication characteristics associated with the set of deduplication groups based on an I/O workload associated with the storage system.

Abstract: There is disclosed techniques for use in managing data storage in storage systems. For example, in one embodiment, there is disclosed a method comprising receiving a request to store data of a data object in a storage system. The method also comprising determining that at least a portion of the data is to be stored in an uncompressed format in the storage system in response to receiving the request. The method also comprising storing at least a portion of the data in the uncompressed format in an allocation unit of a segment in the storage system such that the stored data in the uncompressed format emulates stored data in a compressed format based on the said determination.

Abstract: A technique for managing write requests in a data storage system checks whether newly-arriving data match previously-stored data that have been recorded in a deduplication database. If a match is found, the technique compares mapping metadata for the newly-arriving data with mapping metadata for the matching data. If both sets of metadata point to the same storage location, then the newly-arriving data is a same-data write and a new write to disk is avoided.

Abstract: A technique for writing data in a data storage system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs a batch-relocate operation by gathering a set of mapping metadata for mapping each of the extents in the batch, identifying a set of holes indicated by the set of mapping metadata, and adding the holes to a batch-hole list. The technique then selects a hole, from the batch-hole list, which is big enough to accommodate the compressed extent, and places the compressed extent in the selected hole.

Abstract: A technique for writing data in a file system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs an FS-relocate operation by accessing an FS-hole list provided for the file system and selecting a hole, from the FS-relocate list, which is large enough to accommodate the compressed extent. The technique then places the compressed extent in the selected hole.

Abstract: A method is used in managing deduplication characteristics in a storage system. Deduplication entries stored in a deduplication cache are categorized into a set of deduplication groups based on a data deduplication probability associated with the deduplication entries. A machine learning system is used to dynamically adjust deduplication characteristics associated with the set of deduplication groups based on an I/O workload associated with the storage system.