Abstract: Techniques are used for identifying allocated blocks in a storage system. The techniques may be used to provide, among other things, retrieval of a value associated with a most recent reinitialization of the storage system. For a tier of user data storage in the storage system, a page of storage with the value and a marker indicating that the page marks an end of storage that has been allocated for the tier of user data storage may be identified. Storage may be allocated from a page immediately preceding the identified page.

Abstract: A method, computer program product, and computer system for extending, by a computing device, transaction log page-buffers for Non-Volatile Random Access Memory (NVRAM) onto a solid state drive (SSD). It may be determined whether a bandwidth limit of the NVRAM has reached a threshold bandwidth. An IO may be processed on one of the NVRAM and the SSD based upon, at least in part, whether the bandwidth limit of the NVRAM has reached the threshold bandwidth.

Abstract: A method, computer program product, and computing system for defining a quantity of discrete storage portions within a storage system; entering an expansion mode during which the discrete storage portions are incrementally assigned to at least one processing node until a first assignment level target is achieved; once the first assignment level target is achieved, entering a utilization mode during which the utilization of the assigned discrete portions is increased until a first utilization level target is achieved; and once the first utilization level target is achieved, reentering the expansion mode during which additional discrete storage portions are incrementally assigned to the at least one processing node until a second assignment level target is achieved.

Abstract: A method, computer program product, and computing system for defining a token pool size for a storage system token pool associated with a storage system. An input/output (IO) processing load for the storage system may be determined. The token pool size for the storage system token pool associated with the storage system may be dynamically adjusted based upon, at least in part, one or more changes in the IO processing load determined for the storage system.

Abstract: A method, computer program product, and computer system for virtualizing, by a computing device, a physical metadata space into a virtual metadata space. A translation table from the virtual metadata space to the physical metadata space may be implemented. Metadata in the physical metadata space may be cached based upon the virtual metadata space. The metadata in the physical metadata space may be moved without updating references associated with the metadata in the physical metadata space.

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 response to failure of a data storage drive, data previously stored on the failed drive is rebuilt on a replacement data storage drive by executing drive rebuild jobs on a first set of processor cores. While the data previously stored on the failed data storage drive is being rebuilt, a second set of processor cores is used to process host I/O (Input/Output) requests. The host I/O requests processed by the second set of processor cores may be a first set of host I/O requests processed during the data rebuild. When a current total number of outstanding host I/O requests exceeds a threshold maximum number of outstanding host I/O requests, at least one processor core in the first set of processor cores may be used to process a second set of host I/O requests while the data previously stored on the failed data storage drive is being rebuilt.

Abstract: A technique for performing data reduction applies deduplication principles when performing data compression, providing a form of enhanced compression. The technique obtains a chunk of data that contains multiple extents and applies deduplication actions to identify duplicate extents within the chunk. The technique marks duplicate extents in metadata. Such duplicate extents need not be compressed using conventional data compression, saving computational resources and considerable time.

Abstract: Techniques for providing lifecycle handling of faults associated with a storage appliance. The techniques can include recording information or details of one or more detected faults associated with a storage appliance in a fault database, analyzing the recorded fault information/details by an analytic tool, and determining whether to perform immediate recovery or defer recovery of the detected fault(s) based at least on a recommendation of the analytic tool. In this way, taking the storage appliance offline upon occurrence of a single fault can, for the most part, be avoided. In addition, because the detection of faults is not performed within a fault domain for a filesystem handling files for a single or limited number of volume families, a deduplication domain for the files of the filesystem is not restricted to the single or limited number of volume families.

Abstract: In response to detecting the failure of a data storage drive, a drive rebuild operation is performed. The drive rebuild operation is performed by periodically i) calculating a target rebuild rate that enables data previously stored on the failed data storage drive to be completely rebuilt on at least one other data storage drive within an expected drive rebuild time window, ii) calculating a new value for at least one drive rebuild parameter based on a value for the drive rebuild parameter corresponding to the target rebuild rate indicated by a static rebuild rate data structure and a current level of host I/O (Input/Output) activity, and iii) rebuilding the data previously stored on the failed data storage drive on the at least one other data storage drive for a predetermined time period with the at least one drive rebuild parameter set to the new value for the drive rebuild parameter.

Abstract: A method, computer program product, and computer system for receiving an indication about an amount of background IOs a background scheduler is capable of performing on a plurality of applications, wherein the indication may be based upon, at least in part, one of host IO latency and a rate of the host IO latency being at one of a plurality of levels. One or more applications of the plurality of applications on which to perform the background IOs may be determined. The background IO applications to be performed on the one or more applications of the plurality of applications may be scheduled based upon, at least in part, one of the host IO latency and the rate of the host IO latency being at one of the plurality of levels.

Abstract: Rebalancing the workload of logical devices across multiple nodes may include dynamically modifying preferred paths for one or more logical devices in order to rebalance the I/O workload of the logical devices among the nodes of the data storage system. Determining whether to rebalance the I/O workload between the two nodes may be performed in accordance with one or more criteria. Processing may include monitoring the current workloads of both nodes over time and periodically evaluating, in accordance with the one or more criteria, whether the current workloads of the nodes are imbalanced. Responsive to determining, in accordance with the criteria, that rebalancing of workload between the nodes is needed, the rebalancing may be performed. A notification may be sent to the host regarding any path state changes made as a result of the workload rebalancing.

Abstract: A method of operating a storage appliance is provided.

Abstract: A method, system, and computer program product for encoded virtual block deferred reference counting comprising receiving an input/output (“IO”) request for data, the data associated with a virtual block, updating a reference count structure to reflect the IO request, and updating, out of line from the IO request, one or more reference counts associated with the virtual block to reflect the result of the IO request based on the updated reference count structure.

Abstract: A method, computer program product, and computing system for receiving a candidate data portion; calculating a distance-preserving hash for the candidate data portion; and performing an entropy analysis on the distance-preserving hash to generate a hash entropy for the candidate data portion.

Abstract: A method of correcting errors in a data storage system including a first node, a second node, and shared persistent storage (the first and second nodes being configured to process data storage requests) is provided. The method includes (a) reading cached pages from a first cache disposed within the first node, the cached pages being cached versions of respective persistent pages stored in the shared persistent storage; (b) in response to determining that one of the cached pages is corrupted, requesting that the second node return to the first node a corresponding remote page from a second cache disposed within the second node, the cached page and the remote page each caching a same persistent page of the shared persistent storage; and (c) in response to determining that the remote page received from the second node by the first node is not corrupted, correcting the cached page using the remote page.

Abstract: A method, computer program product, and computer system for identifying, by a computing device, a first amount of storage space reserved by RAID for a RAID rebuild of a failed drive. A second amount of the storage space reserved by a file system may be identified, wherein the storage space may be shared between the RAID and the file system. The RAID rebuild of the failed drive may be performed. The first amount of the storage space may be allocated to the RAID from the second amount of the storage space reserved by the file system.

Abstract: Dirty pages of cached user data are persistently stored to page buffers that are allocated from a page buffer pool in a persistent data storage resource of a data storage system, and are indicated by page descriptors that are stored at a head of a temporally ordered page descriptor ring as the dirty pages are stored to the page buffers. The disclosed technology performs a flush operation by selecting a work-set of non-sequential page descriptors within the page descriptor ring, flushing dirty pages from page buffers indicated by the page descriptors in the work-set to non-volatile data storage drives of the data storage system, and storing, for each one of the page buffers indicated by the page descriptors in the work-set, an indication that the page buffer is available for re-use.

Abstract: A method of operating a storage appliance is provided.

Abstract: A method, computer program product, and computing system for defining a token pool size for a storage system token pool associated with a storage system. An input/output (IO) processing load for the storage system may be determined. The token pool size for the storage system token pool associated with the storage system may be dynamically adjusted based upon, at least in part, one or more changes in the IO processing load determined for the storage system.