Abstract: Techniques are provided for implementing a hash building process and an append hash building process. The hash building process builds in-memory hash entries for bins of keys stored within sorted logs of a log structured merge tree used to store keys of a key-value store. The in-memory hash entries can be used to identify the starting locations of bins of keys within the log structured merge tree so that a key within a bin can be searched for from the starting location of the bin as opposed to having to search the entire log structured merge tree. The append hash building process builds two hashes that can be used to more efficiently locate keys and/or ranges of keys within an unsorted append log that would otherwise require a time consuming binary search of the entire append log.

Abstract: Techniques are provided for a high availability solution (e.g., a network attached storage (NAS) solution) with address preservation during switchover. A first virtual machine is deployed into a first domain and a second virtual machine is deployed into a second domain of a computing environment. The first and second virtual machines are configured as a node pair for providing clients with access to data stored within an aggregate comprising one or more storage structures within shared storage of the computing environment. A load balancer is utilized to manage logical interfaces used by clients to access the virtual machines. During switchover, the load balancer preserves an IP address used to mount and access a data share of the aggregate used by a client.

Abstract: Techniques are provided for storage tier verification checks. A determination is made that a mount operation of an aggregate of a set of volumes stored within a multi-tier storage environment has completed. A first metafile and a second metafile are maintained to track information related to the storage of objects of a volume of the aggregate within a remote object store that is a tier of the multi-tier storage environment. A distributed verification is performed between the first metafile and the second metafile to identify an inconsistency. Accordingly, the first metafile and the second metafile are reconciled to address the inconsistency so that storage information within the first metafile and the second metafile are consistent.

Abstract: One or more techniques and/or computing devices are provided for snapshot creation. For example, a request may be received to create a snapshot of a first storage object, hosted by a first storage controller, having a synchronous replication relationship with a second storage object hosted by a second storage controller. A coordinator workflow is initialized to issue a drain and hold request to a splitter. Responsive to an indication that the splitter has stopped processing and started queuing incoming write operations and has drained current write operations based upon the drain and hold request, snapshot creation requests are sent to the first storage controller and the second storage controller. Responsive to the first storage controller creating a first snapshot of the first storage object and the second storage controller creating a second snapshot of the second storage object, the splitter may be resumed to process write operations.

Abstract: The application relates to writing arbitrarily sized data extents using in-line descriptors, such as headers or footers, into physical blocks to describe the data extents in those physical blocks. Some data extents may be smaller than the size of a physical block, and some data extents may be larger than the size of a physical block. A given physical block therefore includes an in-line descriptor for a data extent in that block, indicating that the data extent starts within that block and also an offset from the beginning of the block to where the data extent starts. The in-line descriptor is included within the block so that when the block is read both the data and the descriptor are read, thereby eliminating performance penalty for reading the descriptor information.

Abstract: A distributed storage system may synchronously apply an Information Lifecycle Management (ILM) policy to objects at ingest. In one embodiment of synchronous ILM, three options are available for a user: balanced, strict, and dual commit. Dual commit refers to the behavior where one will always create two replicated copies in the same site and then apply ILM asynchronously. Strict refers to the behavior where the storage system attempts to apply the ILM policy synchronously on ingest, and if the storage system cannot the ingest of the object will fail. This ensures that the storage system can guarantee that ILM has been applied to recently ingested objects. Balanced refers to the behavior where the storage system attempts to apply ILM synchronously, but if the storage system cannot the storage system may fall-back to dual-commit.

Abstract: Techniques are provided for a snapshot difference interface integrated into an object store data management container. The snapshot difference interface is capable of interpreting an object format and snapshot file system format of snapshots backed up to an object store within objects formatted according to the object format. The snapshot difference interface can identify differences between snapshots, such as files that changed between the snapshots, while the snapshots are still resident within the object store. Because the snapshot difference interface does not retrieve the snapshots from the object store, security is improved, resource and network consumption is reduced, and there is less of an impact upon client I/O processing. Also, a compliance scan for the snapshots can be performed much quicker by skipping already scanned snapshot data from a prior compliance scan.

Abstract: Systems and methods that make use of cluster-level redundancy within a distributed storage management system to address various node-level error scenarios are provided. According to one embodiment, an instance of a key-value (KV) store of a first node of a plurality of nodes of a cluster of a distributed storage system manages storage of data blocks as values and corresponding block identifiers (IDs) as keys. A list of missing block IDs that are in use for one or more volumes associated with the first node but that are missing from the instance of the KV store are identified by performing a data integrity check on the instance of the KV store. After identifying the list of missing block IDs, instead of treating the first node as failed, restoring the missing block IDs by writing redundant data blocks retrieved from other nodes within the cluster to the first node.

Abstract: Methods and systems for protecting virtual machines is provided. One method includes discovering, by a first plugin, from a virtual machine (“VM”) management system, a plurality of VMs that share a logical data store having a plurality of virtual volumes used for storing data for the VMs by a storage system registered with the first plugin and a virtual appliance of the VM management system; obtaining, by the first plugin, from the virtual appliance, metadata and storage layout of a set of virtual volumes used by a VM to store data; using a first application programming interface (API), by the first plugin, for identifying a first set of storage volumes used by the storage system to store data for the set of virtual volumes; and creating, by the first plugin, a consistency group (“CG”) having the identified the first set of storage volumes and generating a snapshot of the CG.

Abstract: Techniques are provided for implementing a unified object format. The unified object format is used to format data in a performance tier (e.g., infrequently accessed data, snapshot data, etc.) into objects that are stored into an object store for low cost, scalable, long term storage compared to storage of the performance tier. With the unified object format, compression of the data may be retained when the data is stored as the objects into the object store. Additional compression may also be provided for the data in the objects. The unified object format includes slot header metadata used to track the location of the data within the object notwithstanding the data being compressed and/or stored at non-fixed boundaries. The slot header metadata may be cached at the performance tier for improved read performance and may be repaired by a repair subsystem (a slot header repair subsystem).

Abstract: Systems and methods that make use of cluster-level redundancy within a distributed storage management system to address various node-level error scenarios are provided. Rather than using a generalized one-size-fits-all approach to reduce complexity, an approach tailored to the node-level error scenario at issue may be performed to avoid doing more than necessary. According to one embodiment, after identifying a missing branch of a tree implemented by a KV store of a first node of a cluster of a distributed storage management system, a branch resynchronization process may be performed, including, for each block ID in the range of block IDs of the missing branch (i) reading a data block corresponding to the block ID from a second node of the cluster that maintains redundant information relating to the block ID; and (ii) restoring the block ID within the KV store by writing the data block to the first node.

Abstract: Systems and methods are described for performing persistent inflight tracking of operations (Ops) within a cross-site storage solution. According to one embodiment, a method comprises maintaining state information regarding a data synchronous replication status for a first storage object of a primary storage cluster and a second storage object of a secondary storage cluster. The method includes performing persistent inflight tracking of I/O operations with a first Op log of the primary storage cluster and a second Op log of the secondary storage cluster, establishing and comparing Op ranges for the first and second Op logs, and determining a relation between the Op range of the first Op log and the Op range of the second Op log to prevent divergence of Ops in the first and second Op logs and to support parallel split of the Ops.

Abstract: A computer-implemented method comprises providing a synchronous replication relationship from one or more storage objects of a first storage node to one or more replicated storage objects of a second storage node, providing an asynchronous replication relationship with an asynchronous update schedule from the one or more storage objects of the first storage node to one or more replicated storage objects of the third storage node to provide a protection configuration, tracking, with the third storage node of the tertiary site, a state of the secondary storage site, automatically performing a failover from the primary storage site to the secondary storage site and activating a synchronous mirror copy for the one or more replicated storage objects of the second storage node, and automatically initiating realignment and reconfiguration of the protection configuration to the tertiary storage site based upon the state of the secondary storage site.

Abstract: Techniques are provided for maintaining and recomputing reference counts in a persistent memory file system of a node. Primary reference counts are maintained for pages within persistent memory of the node. In response to receiving a first operation to link a page into a persistent memory file system of the persistent memory, a primary reference count of the page is incremented before linking the page into the persistent memory file system. In response to receiving a second operation to unlink the page from the persistent memory file system, the page is unlinked from the persistent memory file system before the primary reference count is decremented. Upon the node recovering from a crash, the persistent memory file system is traversed in order to update shadow reference counts for the pages with correct reference count values, which are used to overwrite the primary reference counts with the correct reference count values.

Abstract: Examples described herein are generally directed to providing a fair amount of throughput to multiple clients of a storage system. According to one example, the storage system determines system metrics based upon use of the storage system by the clients. A system load value is calculated based upon the system metrics. The system load value quantifies a load on the storage system by the clients. Client loads, each representing a contribution to the use of the storage system by an individual client, are calculated and expressed as a relative degree or amount of the system load value. A target performance value for a client is calculated based on the client load for the client and a quality of service parameter value provisioned for the client to access the storage system. Based on the target performance value, latency for the client is introduced or removed.

Abstract: Techniques are provided for replay of metadata and data operations. During initial execution of operations, identifiers of objects modified by the execution of each operation are identified and stored in association with the operations. When the operations are to be replayed (e.g., executed again, such as part of a replication operation or as part of flushing content from a cache to persistent storage), the identifiers are evaluated to determine which operations are independent with respect to one another and which operations are dependent with respect to one another. In this way, independent operations are executed in parallel and dependent operations are executed serially with respect to the operations from the dependent operations depend.

Abstract: Techniques are provided for selectively allowing or blocking services from utilizing snapshots. A splitter intercepts and assigns timestamps to operations for execution upon files of a file system. If a snapshot is created while there are no pending operation, then the snapshot is tagged to indicate that the snapshot was created while there were no pending operations, and the snapshot is considered a tagged snapshot. Otherwise, the snapshot is not tagged, and is considered an untagged snapshot. Storage services (e.g., backup applications, lifecycle management applications, applications that consider timestamps of files, etc.) are allowed to utilize tagged snapshots and are blocked from utilizes untagged snapshots in order to maintain consistency.

Abstract: Techniques are provided for utilizing a log to free pages from persistent memory. A log is maintained to comprise a list of page block numbers of pages within persistent memory of a node to free. A page block number, of a page, within the log is identified for processing. A reference count, corresponding to a number of references to the page block number, is identified. In response to the reference count being greater than 1, the reference count is decremented and the page block number is removed from the log. In response to the reference count being 1, the page is freed from the persistent memory and the page block number is removed from the log.

Abstract: Methods and systems for a storage environment are provided. One method includes copying a data unit from a first temporary storage location corresponding to each zoned solid-state drive (ZNS SSD) of a first ZNS SSD set of a storage system to a first XOR module, while determining a first partial horizontal parity using the data unit stored in the first temporary storage location; and determining a vertical parity for each ZNS SSD of the first ZNS SSD set using the data unit provided to the first XOR module in a current cycle and vertical parity determined from a previous cycle.

Abstract: A method for reducing write latency in a distributed file system. A write request that includes a volume identifier is received at a data management subsystem deployed on a node within a distributed storage system. The data management subsystem maps the volume identifier to a file system volume and maps the file system volume to a set of logical block addresses in a logical block device in a storage management subsystem deployed on the node. The storage management subsystem maps the logical block device to a metadata object for the logical block device on the node that is used to process the write request. The mapping of the file system volume to the set of logical block addresses in the logical block device enables co-locating the metadata object with the file system volume on the node, which reduces the write latency associated with processing the write request.