Abstract: A volume rehost tool migrates a storage volume from a source virtual server within a distributed storage system to a destination storage server within the distributed storage system. The volume rehost tool can prevent client access to data on the volume through the source virtual server until the volume has been migrated to the destination virtual server. The tool identifies a set of storage objects associated with the volume, removes configuration information for the set of storage objects, and removes a volume record associated with the source virtual server for the volume. The tool can then create a new volume record associated with the destination virtual server, apply the configuration information for the set of storage objects to the destination virtual server, and allow client access to the data on the volume through the destination virtual server.

Abstract: Techniques are provided for block allocation for persistent memory during aggregate transition. In a high availability pair including first and second nodes, the first node makes a determination that control of a first aggregate is to transition from the first node to the second node. A portion of available free storage space is allocated from a first persistent memory of the first node as allocated pages within the first persistent memory. Metadata information for the allocated pages is updated with an identifier of the first aggregate to create updated metadata information reserving the allocated pages for the first aggregate. The updated metadata information is mirrored to the second node, so that the second node also reserves those pages. Control of the first aggregate is transitioned to the second node. As a result, the nodes do not attempt allocating the same free pages to different aggregates during a transition.

Abstract: One or more techniques and/or computing devices are provided for managing an arbitrary set of storage items using a granset. For example, a storage controller may host a plurality of storage items and/or logical unit numbers (LUNs). A subset of the storage items are grouped into a consistency group. A granset is created for tracking, managing, and/or providing access to the storage items within the consistency group. For example, the granset comprises application programming interfaces (APIs) and/or properties used to provide certain levels of access to the storage items (e.g., read access, write access, no access), redirect operations to access either data of an active file system or to a snapshot, fence certain operations (e.g., rename and delete operations), and/or other properties that apply to each storage item within the consistency group. Thus, the granset provides a persistent on-disk layout used to manage an arbitrary set of storage items.

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, a KV store of a node of a cluster of a distributed storage management system manages storage of data blocks as values and corresponding block IDs as keys. Data integrity errors are reported to the first node in the form of a list of missing block IDs that are in use but missing from the KV store. A metadata resynchronization process may then be caused to be performed, including for each block ID in the list of missing block IDs: (i) reading a data block corresponding to the block ID from another 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 node.

Abstract: Systems and methods for reducing delays between the time at which a need for a resynchronization of data replication between a volume of a local CG and its peer volume of a remote CG is detected and the time at which the resynchronization is triggered (Reseed Time Period) are provided. According to an example, information indicative of the direction of data replication between the volume and the peer volume is maintained within a cache of a node. Responsive to a disruptive operation (e.g., relocation of the volume from a first node to a second node), the Reseed Time Period is lessened by proactively adding a passive cache entry to a cache within the second node at the time the CG relationship is created when the second node represents an HA partner of the first node and prior to the volume coming online when the second node represents a non-HA partner.

Abstract: One or more techniques and/or computing devices are provided for utilizing snapshots for data integrity validation and/or faster application recovery. For example, a first storage controller, hosting first storage, has a synchronous replication relationship with a second storage controller hosting second storage. A snapshot replication policy rule is defined to specify that a replication label is to be used for snapshot create requests, targeting the first storage, that are to be replicated to the second storage. A snapshot creation policy is created to issue snapshot create requests comprising the replication label. Thus a snapshot of the first storage and a replication snapshot of the second storage are created based upon a snapshot create request comprising the replication label. The snapshot and the replication snapshot may be compared for data integrity validation (e.g., determine whether the snapshots comprise the same data) and/or quickly recovering an application after a disaster.

Abstract: Methods, non-transitory machine readable media, and computing devices that dynamically throttle non-priority workloads to satisfy minimum throughput service level objectives (SLOs) are disclosed. With this technology, a determination is made when a number of detection intervals with a violation within a detection window exceeds a threshold, when a current one of the detection intervals is outside an observation area. The detection intervals are identified a violated based on an average throughput for priority workloads within the detection intervals exceeding a minimum throughput SLO. A throttle is then set to rate-limit non-priority workloads, when the number of violated detection intervals within the detection window exceeds the threshold.

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: Techniques are provided for implementing write ordering for persistent memory. A set of actions are identified for commitment to persistent memory of a node for executing an operation upon the persistent memory. An episode is created to comprise a first subset of actions of the set of actions that can be committed to the persistent memory in any order with respect to one another such that a consistent state of the persistent memory can be reconstructed in the event of a crash of the node during execution of the operation. The first subset of actions within the episode are committed to the persistent memory and further execution of the operation is blocked until the episode completes.

Abstract: Systems and methods for managing data storage using a distributed file system are provided. In one example, a relocation event is detected that indicates a relocation is to be initialized. The relocation is initialized by identifying a destination node of a distributed storage system for the relocation of a set of objects in a cluster database, including a logical block device, a corresponding logical aggregate, and a corresponding file system volume. A state of each of the set of objects is changed to offline. The set of objects are then relocated from an originating node of the distributed storage system to the destination node in which the corresponding logical aggregate is relocated after the logical block device and the corresponding file system volume is relocated after the logical aggregate. Finally, the state of each of the set of objects is changed to online.

Abstract: In various examples, data storage is managed using a distributed storage management system that is resilient. Data blocks of a logical block device may be distributed across multiple nodes in a cluster. The logical block device may correspond to a file system volume associated with a file system instance deployed on a selected node within a distributed block layer of a distributed file system. Each data block may have a location in the cluster identified by a block identifier associated with each data block. Each data block may be replicated on at least one other node in the cluster. A metadata object corresponding to a logical block device that maps to the file system volume may be replicated on at least another node in the cluster. Each data block and the metadata object may be hosted on virtualized storage that is protected using redundant array independent disks (RAID).

Abstract: Systems and methods for making a cross-site storage solution resilient towards mediator unavailability are provided. According to one embodiment, a stretched storage system is operable to bring a mediator associated with a primary and secondary distributed storage system back into the role of an arbitrator for peered consistency groups (CGs). A mediator reseed status indicator is maintained for multiple CGs to identify when the mediator’s status information for a CG is stale. When the mediator becomes available and a local CG is identified as the subject of a mediator reseed process, the master node of the primary that hosts a master copy of a dataset for the local CG performs the reseed process, including: (i) causing relationship status information for the local CG to be updated on the mediator to the current state maintained by the primary; and (ii) resetting the mediator reseed status indicator.

Abstract: Systems and methods for automated tuning of Quality of Service (QoS) settings of volumes in a distributed storage system are provided. According to one embodiment, one or more characteristics of a workload of a client to which a storage node of multiple storage nodes of the distributed storage system is exposed are monitored. After a determination has been made that a characteristic meets or exceeds a threshold, (i) information regarding multiple QoS settings assigned to a volume of the storage node utilized by the client is obtained, (ii) a new value of a burst IOPS setting of the multiple QoS settings is calculated by increasing a current value of the burst IOPS setting by a factor dependent upon a first and a second QoS setting of the multiple QoS settings, and (iii) the new value of the burst IOPS setting is assigned to the volume for the client.

Abstract: Systems and methods for making use of non-persistent storage as the journaling storage media for a virtual storage system are provided. According to one embodiment, in order to meet the needs of Extreme Low Latency Workloads while also seeking to provide predictable performance and the lowest possible latency, ephemeral storage of the virtual storage system is used to preserve state information (e.g., in the form of boot arguments and an operation log journal) across a host failure recovery scenario in which the virtual storage system is expected to be redeployed within a compute instance brought up by a cloud environment of a hyperscaler on the same host, thereby providing improved data durability (fewer host failure scenarios that result in lost data) as compared to the use of ephemeral memory of the compute instance and lower write latency than the use of persistent storage provided by the cloud environment.

Abstract: Techniques are provided for persistent hole reservation. For example, hole reservation flags of operations targeting a first storage object of a first node are replicated into replication operations targeting a second storage object of a second node during a transition operation to transition the first storage object and the second storage object from an asynchronous replication state to a synchronous replication state. In another example, the second storage object is grown to a size of a replication punch hole operation that failed due to targeting a file block number greater than an end of size of the second storage object.

Abstract: A storage area network (SAN)-attached storage system architecture is disclosed. The storage system provides strongly consistent distributed storage communication protocol semantics, such as SCSI target semantics. The system includes a mechanism for presenting a single distributed logical unit, comprising one or more logical sub-units, as a single logical unit of storage to a host system by associating each of the logical sub-units that make up the single distributed logical unit with a single host visible identifier that corresponds to the single distributed logical unit. The system further includes mechanisms to maintain consistent context information for each of the logical sub-units such that the logical sub-units are not visible to a host system as separate entities from the single distributed logical unit.

Abstract: Techniques are provided for on-demand serverless disaster recovery. A primary node may host a primary volume. Snapshots of the primary volume may be backed up to an object store. In response to failure, a secondary node and/or an on-demand volume may be created on-demand. The secondary node may provide clients with failover access to the on-demand volume while a restore process restores a snapshot of the primary volume to the on-demand volume. In some embodiments, there was no secondary node and/or on-demand volume while the primary node was operational. This conserves computing resources that would be wasted by otherwise hosting the secondary node and/or on-demand volume while clients were able to access the primary volume through the primary node. Modifications directed to the on-demand volume are incrementally backed up to the object store for subsequently restoring the primary volume after recovery.

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: A system, method, and machine-readable storage medium for performing garbage collection in a distributed storage system are provided. In some embodiments, an efficiency level of a garbage collection process is monitored. The garbage collection process may include removal of one or more data blocks of a set of data blocks that is referenced by a set of content identifiers. The set of slice services and the set of data blocks may reside in a cluster, and a set of probabilistic filters (e.g., Bloom filters) may indicate whether the set of data blocks is in-use. At least one parameter of a probabilistic filter of the set of probabilistic filters may be adjusted (e.g., increased or reduced) if the efficiency level is below the efficiency threshold. Garbage collection may be performed on the set of data blocks in accordance with the set of probabilistic filters.

Abstract: Methods and systems for solid state drives are provided, including assigning a first namespace to a first instance of a storage operating system and a second instance of the storage operating system for enabling read access to a first portion of a flash storage system by the first instance, and read and write access to the second instance; allocating a second namespace to the first instance for exclusive read and write access within a second portion of the flash storage system; generating, by the first instance, a request for the second instance to transfer a data object from the second portion owned by the first instance to the first portion; storing, by the second instance, the data object at the first portion; and updating metadata of the data object at the second portion, the metadata indicating a storage location at the second portion where the data object is stored.