Abstract: Placement of object replicas in a distributed storage system includes, at a first instance, opening a journal for storage of object chunks. An object is received, which comprises one or more chunks. Each chunk comprises one or more storage blocks. The blocks for a single chunk are stored in a single journal. Global metadata for the object is stored, which includes a list of chunks for the object. Local metadata for the chunk is stored, which includes a block list identifying each block of the plurality of blocks. The local metadata is associated with the journal. The journal is later closed. The journal is subsequently replicated to a second instance. The global metadata is updated to reflect the replication, whereas the local metadata is unchanged by the replication.

Abstract: Placement of object replicas in a distributed storage system includes, at a first instance, opening a journal for storage of object chunks. Each journal is associated with a single placement policy. An object is received, which comprises a chunk. The object has a placement policy, and the chunk comprises a plurality of storage blocks. The blocks are stored in a journal that matches the placement policy. Global metadata for the object is stored, which includes a list of chunks for the object. Local metadata for the chunk is stored, which includes a block list identifying each block of the plurality of blocks. The local metadata is associated with the journal. The journal is later closed. The journal is subsequently replicated to a second instance according to the placement policy. The global metadata is updated to reflect the replication, whereas the local metadata is unchanged by the replication.

Abstract: A method may be performed by a device of a group of devices in a distributed data replication system. The method may include storing objects in a data store, at least one or more of the objects being replicated with the distributed data replication system, and conducting a scan of the objects in the data store. The method may further include identifying one of the objects as not having a reference pointing to the object, storing a delete negotiation message as metadata associated with the one of the objects, and replicating the metadata with the delete negotiation message to one or more other devices of the group of devices.

Abstract: Placement of object replicas in a distributed storage system includes, at a first instance, opening a journal for storage of object chunks. Each journal is associated with a single placement policy. An object is received, which comprises a chunk. The object has a placement policy, and the chunk comprises a plurality of storage blocks. The blocks are stored in a journal that matches the placement policy. Global metadata for the object is stored, which includes a list of chunks for the object. Local metadata for the chunk is stored, which includes a block list identifying each block of the plurality of blocks. The local metadata is associated with the journal. The journal is later closed. The journal is subsequently replicated to a second instance according to the placement policy. The global metadata is updated to reflect the replication, whereas the local metadata is unchanged by the replication.

Abstract: A system and method for generating replication requests for objects in a distributed storage system is provided. For a respective object in a distributed storage system the following is performed. Replication policies for the object that have not been satisfied are determined. Replication requests are ranked for the object whose replication policies have not been satisfied based on a number of replicas of the object that need to be created in order to satisfy the replication policies for the object. Replication requests are generated for the object based at least in part on the replication policies for the object that have not been satisfied and on a current state of the distributed storage system. At least a subset of the replication requests for the objects in the distributed storage system are distributed to respective instances of the distributed storage system corresponding to the replication requests for execution.

Abstract: A distributed storage system has multiple instances. There is a plurality of local instances, and at least some of the local instances are at physically distinct geographic locations. Each local instance is configured to store data for a non-empty set of blobs in a plurality of data stores having a plurality of distinct data store types. In addition, each local instance stores metadata for the respective set of blobs in a metadata store distinct from the data stores. There is also a plurality of global instances. Each global instance is configured to store data for zero or more blobs in zero or more data stores and store metadata for all blobs stored at any local or global instance. The system selects one global instance to run a replication module that replicates blobs between instances according to blob policies. Some systems also include dynamic replication based on user needs.

Abstract: Managing placement of object replicas is performed at a first instance of a distributed storage system. One or more journals are opened for storage of object chunks. Each journal is associated with a single placement policy. A first object is received comprising at least a first object chunk. The first object is associated with a first placement policy. The first object chunk is stored in a first journal whose associated placement policy matches the first placement policy. The first journal stores only object chunks for objects whose placement policies match the first placement policy. For the first journal, the receiving and storing operations are repeated for multiple objects whose associated placement policies match the first placement policy, until a first termination condition occurs. Then, the first journal is closed. Subsequently, the first journal is replicated to a second instance of the distributed storage system according to the first placement policy.

Abstract: A system and method for generating replication requests for objects in a distributed storage system is provided. For a respective object in a distributed storage system the following is performed. Replication policies for the object that have not been satisfied are determined. Replication requests are ranked for the object whose replication policies have not been satisfied based on a number of replicas of the object that need to be created in order to satisfy the replication policies for the object. Replication requests are generated for the object based at least in part on the replication policies for the object that have not been satisfied and on a current state of the distributed storage system. At least a subset of the replication requests for the objects in the distributed storage system are distributed to respective instances of the distributed storage system corresponding to the replication requests for execution.

Abstract: A distributed storage system has multiple instances. There is a plurality of local instances, and at least some of the local instances are at physically distinct geographic locations. Each local instance is configured to store data for a non-empty set of blobs in a plurality of data stores having a plurality of distinct data store types. In addition, each local instance stores metadata for the respective set of blobs in a metadata store distinct from the data stores. There is also a plurality of global instances. Each global instance is configured to store data for zero or more blobs in zero or more data stores and store metadata for all blobs stored at any local or global instance. The system selects one global instance to run a replication module that replicates blobs between instances according to blob policies.

Abstract: A system and method for inserting an object into a distributed database is provided. An object to be inserted into a priority queue is received, wherein the object includes a unique identifier and a priority. Next, an index for the object is generated. A row name for the object is then generated based on the index, the priority of the object, and the unique identifier of the object, wherein a lexicographical order of the row name for a higher priority object is smaller than the lexicographical order of the row name for a lower priority object. The object is then inserted into a row of a distributed database using the row name.

Abstract: A method allocates object replicas in a distributed storage system. The method identifies a plurality of objects in the distributed storage system. Each object has an associated storage policy that specifies a target number of object replicas stored at distinct instances of the distributed storage system. The method identifies an object of the plurality of objects whose number of object replicas exceeds the target number of object replicas specified by the storage policy associated with the object. The method selects a first replica of the object for removal based on last access times for replicas of the object, and transmits a request to a first instance of the distributed storage system that stores the first replica. The request instructs the first instance to remove the first replica of the object.

Abstract: A system and method for operating on objects stored in a distributed database is provided. Rows of a distributed database that correspond to an index are identified. The identified rows are sorted lexicographically based on row names of the identified rows. The sorted rows are ordered by priorities of objects corresponding to the sorted rows. The objects corresponding to the sorted rows are operated on in priority order. In some embodiments, the objects are replication requests for replicating data in a distributed storage system, and operating on the objects corresponding to the sorted rows in priority order includes executing the replication requests in priority order to replicate data in the distributed storage system.

Abstract: A method is performed by a device of a group of devices in a distributed data replication system. The method includes storing an index of objects in the distributed data replication system, the index being replicated while the objects are stored locally by the plurality of devices in the distributed data replication system. The method also includes conducting a scan of at least a portion of the index and identifying a redundant replica(s) of the at least one of the objects based on the scan of the index. The method further includes de-duplicating the redundant replica(s), and updating the index to reflect the status of the redundant replica.

Abstract: A method is performed by a device of a group of devices in a distributed data replication system. The method includes storing an index of objects in the distributed data replication system, the index being replicated while the objects are stored locally by the plurality of devices in the distributed data replication system. The method also includes conducting a scan of at least a portion of the index and identifying a redundant replica(s) of the at least one of the objects based on the scan of the index. The method further includes de-duplicating the redundant replica(s), and updating the index to reflect the status of the redundant replica.

Abstract: A method performed by two or more devices of a group of devices in a distributed data replication system may include receiving a group of chunks having a same unique temporary identifier, the group of chunks comprising an object to be uploaded; creating an entry for the object in a replicated index, the entry being keyed by the unique temporary identifier, and the replicated index being replicated at each of the two or more devices; and determining, by an initiating device of the two or more devices, that a union of the group of chunks contains all data of the object. The method may also include calculating a content-based identifier to the object; creating another entry for the object in the replicated index, the other entry being keyed by the content-based identifier; and updating the replicated index to point from the unique temporary identifier to the content-based identifier.

Abstract: A distributed storage system has a plurality of instances. A computer system simulates the state of the distributed storage system. The system obtains a current state of the distributed storage system and replication policies for objects in the distributed storage system. Each replication policy specifies criteria for placing copies of the relevant objects among the plurality of instances. The system receives proposed modifications to the state of the distributed storage system and simulates the state of the distributed storage system over time based on the current state of the distributed storage system, current statistical trends in the state of the distributed storage system, the replication policies for the objects in the distributed storage system, and the proposed modifications to the state of the distributed storage system. One or more reports are generated relating to time evolution of the state of the distributed storage system based on the simulation.

Abstract: A method for managing multiple generations of an object within a distributed storage system is implemented at a computing device. The computing device receives metadata and content of a first generation of an object from a first client connected to the distributed storage system and stores the first generation's metadata and content within a first storage sub-system. The computing device receives metadata and content of a second generation of the object from a second client connected to the distributed storage system and stores the second generation's metadata and content within a second storage sub-system. The computing device independently replicates the first generation's metadata and content from the first storage sub-system to the second storage sub-system and replicates the second generation's metadata and content from the second storage sub-system to the first storage sub-system such that both storage sub-systems include a replica of the object's first and second generations.

Abstract: A system and method for simulating a state of a distributed storage system is provided. A current state of a distributed storage system and replication policies for the objects in the distributed storage system is obtained. Proposed modifications to the current state of the distributed storage system are received. The state of the distributed storage system is simulated over time based on the current state of the distributed storage system, the replication policies for the objects in the distributed storage system, and the proposed modifications to the current state of the distributed storage system. Then reports relating to the time evolution of the current state of the distributed storage system are generated based on the simulation.

Abstract: A method performed by two or more devices of a group of devices in a distributed data replication system may include receiving a group of chunks having a same unique temporary identifier, the group of chunks comprising an object to be uploaded; creating an entry for the object in a replicated index, the entry being keyed by the unique temporary identifier, and the replicated index being replicated at each of the two or more devices; and determining, by an initiating device of the two or more devices, that a union of the group of chunks contains all data of the object. The method may also include calculating a content-based identifier to the object; creating another entry for the object in the replicated index, the other entry being keyed by the content-based identifier; and updating the replicated index to point from the unique temporary identifier to the content-based identifier.

Abstract: A method performed by two or more devices of a group of devices in a distributed data replication system may include receiving a group of chunks having a same unique temporary identifier, the group of chunks comprising an object to be uploaded; creating an entry for the object in a replicated index, the entry being keyed by the unique temporary identifier, and the replicated index being replicated at each of the two or more devices; and determining, by an initiating device of the two or more devices, that a union of the group of chunks contains all data of the object. The method may also include calculating a content-based identifier to the object; creating another entry for the object in the replicated index, the other entry being keyed by the content-based identifier; and updating the replicated index to point from the unique temporary identifier to the content-based identifier.