Dell Products Inc.

Alexander Shknevsky

Vamsi K Vankamamidi

Uri Shabi

Oran Asher Baruch

Maor Rahamim

Oran Baruch

Vladimir Shveidel

Amit Zaitman

Ajay Karri

Kurt W Everson

A method of managing end-of-life processing of data blocks includes performing a decref procedure for a chunk of data, the decref procedure decrementing reference counts for respective blocks of the chunk of data, and deferring performance of an end-of-life procedure for a plurality of blocks of the chunk of data whose reference counts become zero as a result of performing the decref procedure. The method further includes, upon performing a data consolidation procedure after performing the decref procedure, performing the end-of-life procedure on the plurality of blocks.

End-of-life data page processing

For a flush request for a first block of user data directly stored into a physical block of non-volatile data storage, allocating a virtual layer block, and storing, in the virtual layer block, a first set of virtual block pointers indicating pages of the first block within the physical block. Pointers to the virtual block pointers in the first set are then stored into a leaf layer of a logical address mapping tree. The virtual layer block is identified for a subsequent flush request issued for a second block of user data directly stored into the physical block, and a second set of virtual block pointers indicating pages of the second block within the physical block is stored in the virtual layer block. Pointers to the virtual block pointers in the second set are stored into a leaf layer node of another logical address mapping tree.

Flushing directly ingested user data

Techniques for keeping on-disk, physical deduplication ('dedupe') index levels up to date to increase the efficiency of data deduplication in storage systems. The techniques include providing a plurality of dedupe indexes across a memory level and a disk level of a storage system, in which the plurality of dedupe indexes include an in-memory dedupe index at the memory level, and an on-disk dedupe index at the disk level. The techniques include applying a plurality of eviction rules regarding evicting entries of the on-disk dedupe index, in which the plurality of eviction rules avoid random evictions of entries from the on-disk dedupe index. The techniques include, in response to applying the plurality of eviction rules, identifying a plurality of entries of the on-disk dedupe index as eviction candidates. The techniques include evicting the identified eviction candidates from the on-disk dedupe index.

Method to keep on-disk physical deduplication index layer up to date

A method, computer program product, and computing system for maintaining a pointer quantity count for each of a plurality of virtual mapping groups, wherein each virtual mapping group is associated with a duplicative data portion within a storage platform and each pointer quantity count defines the number of pointers included within the corresponding virtual mapping group; and obtaining a hash value for a specific duplicative data portion associated with a specific virtual mapping group if a specific pointer quantity count for the specific virtual mapping group is reduced to zero.

System and method for hash-based data deduplication

A method, computer program product, and computing system for expanding the lifetime of virtual entries in a data storage system. A deduplication function of a virtual layer of a data storage system is monitored, a reference count of a virtual entry is incremented when a data page is written to a physical layer of the data storage system and the reference count of the virtual entry is decremented when a data page is deleted from the virtual layer. The virtual entry in the virtual layer is maintained when the reference count reaches a predetermined value and the virtual entry is reclaimed when a predetermined action of the data storage system is to be performed.

System and method for expanding the lifetime of virtual entries in data storage systems

Techniques for achieving efficient removal of stale index entries from on-drive deduplication indexes using hash prefix indexing. The techniques include providing an on-drive dedupe index that includes a plurality of index entries. Each index entry includes a hash value of a data page, and an address associated with a storage location of the data page. Each index entry is assigned to a bucket defined by a respective hash prefix. The techniques include, for each data page associated with a reference count decremented to zero, logging a hash prefix and a storage address of the data page. The techniques include, for each bucket, constructing an address bag, storing, in the address bag, logged addresses whose corresponding hash prefix is the same as the respective hash prefix defining the bucket, and removing, from the bucket, each stale index entry that includes an address matching one of the addresses in the address bag.

Efficient removal of stale entries from on-drive deduplication hash tables using hash prefix indexing

Techniques for limiting or reducing storage accessibility 'hiccups' in active-active clustered systems that perform large writes. The techniques can include executing, by a surviving, failover, or rebooted node of an active-active clustered system, a specialized recovery protocol that includes treating each large write request from a host computer as a plurality of small write requests while execution of the specialized recovery protocol is in progress, draining all dedicated sub-ubers for a primary and secondary node of the active-active clustered system, and, having completed execution of the specialized recovery protocol, resuming normal treatment of large write requests from the host computer. In this way, the need and complexity of managing large writes and maintaining their corresponding sub-uber information during recovery from a forced reboot, crash, or disaster involving the primary or secondary node can be avoided, and storage accessibility hiccups due to performing the large writes can be limited or reduced.

Low hiccup time fail-back in active-active dual-node storage systems with large writes

A technique of managing writes in a data storage system includes receiving I/O requests specifying data to be written, storing a set of the data to be written in an extent of a data log, and preventing data reduction from being performed on the set of data in the extent for at least a specified time interval, said time interval enabling portions of the set of data to be overwritten with new data and rendering data reduction of such portions unnecessary.

Avoiding data reduction debt for quickly overwritten data

Techniques of the present disclosure can include: identifying blocks of storage available for allocation; generating a list denoting an allocation order of storage chunks of the blocks; receiving a write I/O operation that writes data to a first logical address; allocating a storage chunk in accordance with the allocation order of the list, wherein a first block includes the storage chunk and a second storage chunk; storing the first data in the storage chunk of the first block; removing the second storage chunk from the list; and creating a mapping between the first logical address and the first block indicating the second storage chunk is reserved for storing content written to a logical address included in a volume logical address range comprising the first logical address. The allocation order can spread allocation distance between blocks and chunks of the same block to avoid contention during flushes.

Storage allocation techniques for large writes based on reserving one or more additional chunks of a block

A method, computer program product, and computing system for generating a page buffer pool within a data journal of a storage node. A plurality of IO operations may be processed on a storage array using the storage node. A plurality of pages may be persisted in a plurality of page buffers within the page buffer pool based upon, at least in part, the processing of the plurality of IO operations. For each page buffer in the page buffer pool, a hash of the page buffer may be generated, thus defining a page buffer hash. The page buffer hash may be stored in a page descriptor associated with the page buffer.

Storage management system and method

A data storage system non-disruptively transitions from using a ring-based write log to using a pool-based write log for buffering data being written to persistent secondary storage. The system initially creates the pool-based write log based on contents of the ring-based write log, and begins to mirror updates of the ring-based write log to the pool-based write log to establish synchronism. Subsequently, and based on an update flag indicating that an update process for the system has not yet completed, the system continues to mirror updates of the ring-based write log to the pool-based write log to maintain synchronism therebetween. Subsequently, and based on the update flag indicating that the update process for the system has completed, the system commences exclusive use of the pool-based write log and making the ring-based write log available for eventual removal.

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Fair Lawn, NJ, United States of America

Alexander Shknevsky