Abstract: At the time of deleting a snapshot, a storage system can allocate a buffer in volatile memory, scan a plurality of logical block address (LBA)-to-virtual block address (VBA) mappings included in a first tree metadata structure of the snapshot, and, for each scanned LBA-to-VBA mapping, identify in a second tree metadata structure a VBA-to-physical block address (PBA) mapping referenced by the LBA-to-VBA mapping. If the VBA-to-PBA mapping is exclusively owned by the snapshot, the storage system can add a record to the buffer that includes the VBA specified in the VBA-to-PBA mapping. The storage system can subsequently sort the records added to the buffer in VBA order and sequentially process the sorted records to remove their corresponding VBA-to-PBA mappings from the second tree metadata structure.

Abstract: A failure analysis system identifies a root cause of a failure (or other health issue) in a virtualized computing environment and provides a recommendation for remediation. The failure analysis system uses a model-based reasoning (MBR) approach that involves building a model describing the relationships/dependencies of elements in the various layers of the virtualized computing environment, and the model is used by an inference engine to generate facts and rules for reasoning to identify an element in the virtualized computing environment that is causing the failure. Then, then the failure analysis system uses a decision tree analysis (DTA) approach to perform a deep diagnosis of the element, by traversing a decision tree that was generated by combining the rules for reasoning provided by the MBR approach, in conjunction with examining data collected by health monitors. The result of the DTA approach is then used to generate the recommendation for remediation.

Abstract: The disclosure herein describes storing data using a capacity data storage tier and a smaller performance data storage tier. The capacity data storage tier includes capacity data storage hardware configured to store log-structured leaf pages (LLPs), and the performance data storage tier includes performance data storage hardware. A virtual address table (VAT) includes a set of virtual address entries referencing the LLPs. A tree-structured index includes index nodes referencing the set of virtual address entries of the VAT. Data to be stored is received, and at least a first portion of metadata associated with the received data is stored in the LLPs using the VAT, and at least a second portion of metadata associated with the received data is stored in the performance data storage tier. The architecture reduces space usage of the performance data storage tier.

Abstract: Scalable segment cleaning for log-structured file systems (LFSs) includes determining counts of segment cleaners and virtual nodes, with each virtual node being associated with a plurality of objects. Each virtual node is assigned to a selected segment cleaner. Based at least on the assignments, performing, for each virtual node, segment cleaning of the objects by the assigned segment cleaner. A portion, less than all, of the virtual nodes are reassigned to a newly selected segment cleaner based on a change of the count of the segment cleaners and/or a change of the count of the virtual nodes. Based at least on the reassignments, segment cleaning of the objects is performed, for each reassigned virtual node, by the reassigned segment cleaner. In some examples, the objects comprise virtual machine disks (VMDKs) and the segment cleaning uses a segment usage table (SUT) to track segment usage and identify segment cleaning candidates.

Abstract: System and method for managing copy-on-write (COW) B tree structures for metadata of storage objects stored in a storage system determine, when a request to modify a target storage object stored in the storage system that requires a modification of a target leaf node in a B tree structure for metadata of the target storage object is received, whether an operation sequence number of the target leaf node is greater than a snapshot sequence number of a parent snapshot of a running point of the B tree structure. When the operation sequence number is greater than the snapshot sequence number, the target leaf mode is modified in place without copying the target leaf node. When the operation sequence number is not greater than the snapshot sequence number, the target leaf node is copied as a new leaf node for the B tree structure and the new leaf node is modified.

Abstract: A robot joint configuration determining method, a robot using the same, and a computer readable storage medium are provided. The method includes: simulating a joint model of a first joint of the robot using first motion deviation data to obtain first result data; simulating the joint model using second motion deviation data to obtain second result data; taking the motion deviation data corresponding to one of the first result data and the second result data meeting one or more preset conditions as a target motion deviation data for the first joint; and determining type information of a reducer in a configuration information of the first joint based on the target motion deviation data. In the present disclosure, the motion deviation of the first joint that is relatively accurate can be obtained through the results of the two simulations.

Abstract: A method for block addressing is provided. The method includes moving content of a data block referenced by a logical block address (LBA) from a first physical block corresponding to a first physical block address (PBA) to a second physical block corresponding to a second PBA, wherein prior to the moving a logical map maps the LBA to a middle block address (MBA) and a middle map maps the MBA to the first PBA and in response to the moving, updating the middle map to map the MBA to the second PBA instead of the first PBA.

Abstract: A method for verifying a consistency of snapshot metadata maintained in an ordered data structure for a plurality of snapshots in a snapshot hierarchy is provided. The method includes identifying a first plurality of nodes maintained in a first ordered data structure for a first snapshot that is a child of a second snapshot; for a first node of the first plurality of nodes, verifying the first node by checking for the first node in a second node map maintained in memory for the second snapshot, wherein the second node map includes a plurality of verified nodes in a second ordered data structure; and based on whether the first node is in the second node map: adding the first node to a first node map maintained in memory for the first snapshot, wherein the first node map includes verified nodes of the first plurality of nodes; or triggering an alarm.

Abstract: A method for encrypting data in one or more data blocks is provided. The method receives a first data block to be written to a physical storage that includes one or more physical disks. The method applies a first random tweak to data indicative of the first data block to generate a first encrypted data block, and writes the first encrypted data block and the first random tweak to a first physical block of the physical storage. The method receives a second data block to be written to the physical storage. The method then applies a second random tweak, different than the first random tweak, to data indicative of the second data block to generate a second encrypted data block, and writes the second encrypted data block and the second random tweak to a second physical block of the physical storage.

Abstract: The application discloses a placement system for a door of a wafer pod, including a loadport. A docking interface is formed in the loadport, a placement mechanism is arranged on one side surface of the loadport, and includes a swing component, a follower component, and a docking plate. The swing component and the follower component are respectively connected to the docking plate, and the swing component can drive the docking plate to place the docking plate obliquely above the docking interface. By utilizing the space at the top of the loadport, the structural layout of the loadport is more reasonable; and the docking plate is placed nearly horizontally after the door is placed at a designated position, and provides a supporting force to the door, so that dependence on the vacuum suction is decreased, thereby avoiding the influences due to fluctuations of air pressure.

Abstract: Linked clone read performance (e.g., retrieving data) is improved at least by minimizing the number of input/output (I/O) operations. For a child clone, a local logical extent and an inherited logical extent are generated. The local logical extent comprises a logical block address (LBA) for data in a data region of the child clone and a physical sector address (PSA) corresponding to the LBA for the data in the data region of the child clone. The inherited logical extent spans logical extents that are accessible to the child clone. The inherited logical extent comprises an LBA for data in a data region of an ancestor of the child clone and a corresponding identifier (ID) of the ancestor. Data for an LBA in a read request may be rapidly found in the child clone (local logical extent) or an ancestor (inherited logical extent).

Abstract: The present disclosure is related to methods, systems, and machine-readable media for determining shared nodes between snapshots using probabilistic data structures. A unique identifier can be assigned to each node of a first tree data structure corresponding to a first snapshot of a virtual computing instance (VCI). A first probabilistic data structure representing the first tree data structure can be created that includes hashes of the identifiers assigned to the nodes of the first tree data structure. A unique identifier can be assigned to each node of a second tree data structure corresponding to a second snapshot of the VCI. A second probabilistic data structure representing the second tree data structure can be created that includes hashes of the identifiers assigned to the nodes of the second tree data structure.

Abstract: Techniques for efficiently managing a file clone from a filesystem which supports efficient volume snapshots are provided. In some embodiments, a system may receive an instruction to remove the file clone from the filesystem. The file clone may be a point-in-time copy of metadata of an original file. The system may further—for a file map entry in a filesystem tree associated with the file clone, the file map entry indicating a data block—decrement a reference count in a reference count entry associated with the file map entry. The reference count entry may be stored in the filesystem tree according to a key and the key may comprise an identification of the original file. The system may further reclaim the data block in a storage system when the reference count is zero.

Abstract: Techniques for using data mirroring across regions to reduce the likelihood of losing objects in a cloud object storage platform are provided. In one set of embodiments, a computer system can upload first and second copies of a data object to first and second regions of the cloud object storage platform respectively, where the first and second copies are identical. The computer system can then attempt to read the first copy of the data object from the first region. If the read attempt fails, the computer system can retrieve the second copy of the data object from the second region.

Abstract: The location of resources for file services are located within the same site, thereby eliminating or reducing performance issues caused by cross-site accesses in a stretched cluster environment. A file server placement algorithm initially places file servers at a site based at least in part on host workload and affinity settings, and can perform failover to move the file servers to a different location (e.g., to a different host on the same site or to another site) in the event of a failure of the host where the file servers were initially placed. File servers may be co-located with clients at a location based on client latencies and site workload. Failover support is also provided in the event that the sites in the stretched cluster have different subnet addresses.

Abstract: Techniques for using erasure coding in a single region to reduce the likelihood of losing objects in a cloud object storage platform are provided. In one set of embodiments, a computer system can upload a plurality of data objects to a region of a cloud object storage platform, where the plurality of data objects including modifications to a data set. The computer system can further compute a parity object based on the plurality of data objects, where the parity object encodes parity information for the plurality of data objects. The computer system can then upload the parity object to the same region where the plurality of data objects was uploaded.

Abstract: A method for of input/output (I/O) quiescing in a write-ahead-log (WAL)-based storage system comprising a WAL, is provided. The method generally includes receiving a request to process a control operation for the storage system, determining whether a memory buffer includes payload data for one or more write requests previously received for the storage system and added to the WAL, forcing a flush of the payload data in the memory buffer to a persistent layer of the storage system when the memory buffer includes the payload data, and processing the control operation subsequent to completing the asynchronous flush, without waiting for processing of one or more other write requests in the WAL corresponding to payload data that was not added to the memory buffer prior to receiving the request to process the control operation.

Abstract: An example method of upgrading a distributed storage object from a first version to a second version includes: querying metadata of a first component configured according to the first version of the distributed storage object, the metadata defining extents of data on a disk group of the first component; populating, for a second component configured according to the second version of the distributed storage object, logical and middle maps based on the metadata such that initial entries in the logical map point to initial entries in the middle map, and the initial entries in the middle map point to physical addresses of the disk group of the first component; and reading the data from the disk group of the first component and writing the data to a disk group of the second component while updating the initial entries in the middle map.

Abstract: Techniques for using erasure coding across multiple regions to reduce the likelihood of losing objects in a cloud object storage platform are provided. In one set of embodiments, a computer system can upload each of a plurality of data objects to each of a plurality of regions of the cloud object storage platform. The computer system can further compute a parity object based on the plurality of data objects, where the parity object encodes parity information for the plurality of data objects. The computer system can then upload the parity object to another region of the cloud object storage platform different from the plurality of regions.

Abstract: A method for managing replication of cloned files is provided. Embodiments include determining, at a source system, that a first file has been cloned to create a second file. Embodiments include sending, from the source system to a replica system, an address of the first extent and an indication that a status of the first extent has changed from non-cloned to cloned. Embodiments include changing, at the replica system, a status of a second extent associated with a replica of the first file on the replica system from non-cloned to cloned and creating a mapping of the address of the first extent to an address of the second extent on the replica system. Embodiments include creating, at the replica system, a replica of the second file comprising a reference to the address of the second extent on the replica system.