Abstract: A method for cleaning an object storage having a plurality of segments is provided. Each segment includes an identifier through which the segment is accessed. The method identifies a first segment in the plurality of segments. The first segment includes a first identifier and a first size. The method determines that a utilization ratio for the first segment is below a threshold. As a result, the method generates a second segment from the first segment, such that the second segment includes a second identifier that is the same as the first identifier and a second size that is smaller than the first size. The method then writes the second segment to the object storage.

Abstract: Techniques for the increased efficiency of storing data objects storage in the object storage of a software designed data center (SDDC) are provided. The techniques include the efficient storage of data, while enabling snapshots of each updating of the data. The snapshots of the data may be efficiently recovered via the techniques. Difference-level mappings for each snapshot are encoded in compact self-balancing data trees included in the object's metadata. The metadata mappings include mappings between various address spaces employed by the SDDC, as well as the address spaces employed by data stores that store the data on physical medium. Because the metadata is efficiently structured, the metadata for an object may be cached for quick lookups during data access and/or snapshot recovery. The techniques also provide low-latency recovery and/or system rollback in the event of any failure in the SDDC.

Abstract: Techniques for the increased efficiency of storing data objects storage in the object storage of a software designed data center (SDDC) are provided. The techniques include the efficient storage of data, while enabling snapshots of each updating of the data. The snapshots of the data may be efficiently recovered via the techniques. Difference-level mappings for each snapshot are encoded in compact self-balancing data trees included in the object's metadata. The metadata mappings include mappings between various address spaces employed by the SDDC, as well as the address spaces employed by data stores that store the data on physical medium. Because the metadata is efficiently structured, the metadata for an object may be cached for quick lookups during data access and/or snapshot recovery. The techniques also provide low-latency recovery and/or system rollback in the event of any failure in the SDDC.

Abstract: Techniques for the increased efficiency of storing data objects storage in the object storage of a software designed data center (SDDC) are provided. The techniques include the efficient storage of data, while enabling snapshots of each updating of the data. The snapshots of the data may be efficiently recovered via the techniques. Difference-level mappings for each snapshot are encoded in compact self-balancing data trees included in the object's metadata. The metadata mappings include mappings between various address spaces employed by the SDDC, as well as the address spaces employed by data stores that store the data on physical medium. Because the metadata is efficiently structured, the metadata for an object may be cached for quick lookups during data access and/or snapshot recovery. The techniques also provide low-latency recovery and/or system rollback in the event of any failure in the SDDC, including when the failure occurs while uploading a snapshot.

Abstract: Techniques for tiering data to a cold storage tier of a cloud object storage platform are provided. In one set of embodiments, a computer system can identify one or more old snapshots of a data set that reside in a first storage tier of the cloud object storage platform, where the one or more old snapshots are snapshots that are unlikely to be deleted from the cloud object storage platform within a period of N days. The computer system can further, for each snapshot in the one or more old snapshots: identify one or more data blocks in the snapshot that are superseded by a more recent snapshot in the one or more old snapshots; write the one or more data blocks to a second (i.e., cold) storage tier of the cloud object storage platform that has a lower storage cost than the first storage tier; and cause the one or more data blocks to be deleted from the first storage tier.

Abstract: The present disclosure is related to methods, systems, and machine-readable media for supporting deduplication in object storage using subset hashes. A plurality of hashes of a plurality of blocks of a plurality of log segments can be received from a software defined data center, wherein each block corresponds to a respective logical address. Each of the plurality of logical addresses can be associated with a respective sequentially-allocated chunk identifier in a logical map. A subset hash comprising a hash of a subset of the plurality of blocks can be determined that corresponds to a contiguous range of the plurality of logical addresses. A search of a hash map for the subset hash can be performed to determine if the subset hash is a duplicate. The subset of the plurality of blocks can be deduplicated responsive to a determination that the subset hash is a duplicate.

Abstract: The present disclosure is related to methods, systems, and machine-readable media for supporting deduplication in file storage using file chunk hashes. A hash of a chunk of a log segment can be received from a software defined data center. A chunk identifier can be associated with the hash in a hash map that stores associations between sequentially-allocated chunk identifiers and hashes. The chunk identifier can be associated with a logical address corresponding to the chunk of the log segment in a logical map that stores associations between the sequentially-allocated chunk identifiers and logical addresses. A search of the hash map can be performed to determine if the chunk is a duplicate, and the chunk can be deduplicated responsive to a determination that the chunk is a duplicate.

Abstract: Techniques for concurrently supporting virtual non-uniform memory access (virtual NUMA) and CPU/memory hot-add in a virtual machine (VM) are provided. In one set of embodiments, a hypervisor of a host system can compute a node size for a virtual NUMA topology of the VM, where the node size indicates a maximum number of virtual central processing units (vCPUs) and a maximum amount of memory to be included in each virtual NUMA node. The hypervisor can further build and expose the virtual NUMA topology to the VM. Then, at a time of receiving a request to hot-add a new vCPU or memory region to the VM, the hypervisor can check whether all existing nodes in the virtual NUMA topology have reached the maximum number of vCPUs or maximum amount of memory, per the computed node size. If so, the hypervisor can create a new node with the new vCPU or memory region and add the new node to the virtual NUMA topology.

Abstract: Techniques for tiering data to a cold storage tier of a cloud object storage platform are provided. In one set of embodiments, a computer system can identify one or more old snapshots of a data set that reside in a first storage tier of the cloud object storage platform, where the one or more old snapshots are snapshots that are unlikely to be deleted from the cloud object storage platform within a period of N days. The computer system can further, for each snapshot in the one or more old snapshots: identify one or more data blocks in the snapshot that are superseded by a more recent snapshot in the one or more old snapshots; write the one or more data blocks to a second (i.e., cold) storage tier of the cloud object storage platform that has a lower storage cost than the first storage tier; and cause the one or more data blocks to be deleted from the first storage tier.

Abstract: Techniques for recovering metadata associated with data backed up in cloud object storage are provided. In one set of embodiments, a computer system can create a snapshot of a data set, where the snapshot includes a plurality of data blocks of the data set that have been modified since the creation of a prior snapshot of the data set. The computer system can further upload the snapshot to a cloud object storage platform of a cloud infrastructure, where the snapshot is uploaded as a plurality of log segments conforming to an object format of the cloud object storage platform, and where each log segment includes one or more data blocks in the plurality of data blocks, and a set of metadata comprising, for each of the one or more data blocks, an identifier of the data set, an identifier of the snapshot, and a logical block address (LBA) of the data block.

Abstract: Solutions for managing archived storage include receiving, at a first node, a snapshot comprising object data (e.g., a virtual machine disk snapshot) from a second node (e.g., a software defined data center), and storing the snapshot in a tiered structure that includes a data tier and a metadata tier. Snapshots may be used for fail-over operations and/or backups, to support disaster recovery. The data tier comprises a log-structured file system (LFS), and the metadata tier comprises a content addressable storage (CAS) identifying addresses within the LFS. The metadata tier also comprises a logical layer indicating content in the CAS. Segment cleaning of the data tier is performed using a segment usage table (SUT). Some examples include performing a fail-over operation from the second node to a third node using at least the stored snapshot for workload recovery. In some examples, the CAS comprises a log-structured merge-tree (LSM-tree).

Abstract: A method for managing metadata for data stored in a cloud storage is provided. The method receives, at a first of a plurality of metadata servers, information associated with an object stored in the cloud storage, the information comprising a plurality of LBAs for where the object is stored. Each metadata server allocates contiguous chunk IDs for a group of objects. The method generates a new chunk ID for the object, which is a combination of a unique fixed value and a monotonically incrementing local value associated with each LBA, such that a first LBA is mapped to a first chunk ID having a first local value and a next LBA is mapped to a second chunk ID having the first local value incremented as a second local value. The method stores the new chunk ID and other metadata in one or more tables stored in a metadata storage.

Abstract: Disclosed are various embodiments for providing content to virtual machines. A request for content can be received, wherein the request originates from a virtual machine hosted by the computing device, comprises a unique identifier for the content, and is received from the virtual machine through an inter-process communication mechanism. The unique identifier can be validated. Content can then be retrieved using the unique identifier. A copy of the content can then be provided to the virtual machine in response to validation of the unique identifier, the content being provided to the virtual machine through the inter-process communication mechanism.

Abstract: Examples provide input and output request block size compatibility. A storage filter converts input and output (IO) requests associated with a first data block size into modified IO requests compatible with a data storage organized in a second data block size where the first data block size is different than the first data block size. The storage filter translates read IO requests for a smaller block size into modified read requests for a data storage organized with a larger data block size. Write IO requests for smaller block size are converted into modified write IO requests for larger data block size data storage. The storage filter also converts read IO requests generated for larger block size into smaller block size read IO requests. Likewise, the storage filter also translates write IO requests corresponding to larger data block size into modified write IO requests of smaller block size.

Abstract: A method for precisely counting guest branch instructions in a virtualized computer system is described. In one embodiment, guest instructions execute in a direct execution mode of the virtualized computer system. The direct execution mode operates at a first privilege level having a lower privilege than a second privilege level. A branch count of previously executed first privilege level branch instructions is maintained as instructions execute. Execution of a first privilege level branch instruction caused by a control transfer to the direct execution mode is detected. Responsive to the detection, a guest branch instruction count is determined based on the first privilege level branch count.

Abstract: Replay-time-only functionalities in a computer program are executed only during replay in a virtual machine and are skipped outside of replay. If a replay-time-only functionality is detected during the replay of a program execution in a virtual machine, the replay may be paused and the virtual machine state may be saved. The replay-time-only core functionality is executed. When this execution is complete, a prior state of the virtual machine may be restored and the replay may be resumed.

Abstract: A method for synchronizing the handling of events in a computer using the Advanced Configuration and Power Interface (ACPI) standard is presented, wherein an ACPI Notification Queue (ANQ) is provided to store events, such that such events can be handled in first-in-first-out order.

Abstract: A method of data communication between a first virtual machine and a second virtual machine is disclosed. The second virtual machine is executing in a record/replay mode. Data from the first virtual machine is copied to a first queue. The first queue receives the data from the first virtual machine. The first queue has a header section and a data section, wherein the header section being write protected and stores a tail pointer of the data in the first queue. The tail pointer is updated in the header section. This update of the tail pointer causes a page fault, which is handled-through a page fault handler. The handling includes copying the data from the first queue to a second queue. The second queue being configured to receive a copy of the data and to allow the second virtual machine to access the copy of the data.

Abstract: A method for synchronizing the handling of events in a computer using the Advanced Configuration and Power Interface (ACPI) standard is presented, wherein an ACPI Notification Queue (ANQ) is provided to store events, such that such events can be handled in first-in-first-out order.

Abstract: Replay-time-only functionalities in a computer program are executed only during replay in a virtual machine and are skipped outside of replay. If a replay-time-only functionality is detected during the replay of a program execution in a virtual machine, the replay may be paused and the virtual machine state may be saved. The replay-time-only core functionality is executed. When this execution is complete, a prior state of the virtual machine may be restored and the replay may be resumed.