Wandisco Inc.

Cirata, Inc.

Yeturu Aahlad

Michael Parkin

Jagane Sundar

Ramakrishna Thurimella

Naeem Akhtar

Konstantin V Shvachko

Michal Dobisek

Granville Lynn Barnett

Christopher Mackey

Rahul Bhargava

Plamen Jeliazkov

Mohammad Naeem Akhtar

Naeem Akthar

David James Richards

James Milton Campigli

Mark McKeown

Mark Patrick McKeown

Kostantin V Shvachko

Micahel Parkin

Plamen Jeliazkov Jeliazkov

Mark Mckeown

First replicated state machines may execute a sequence of ordered agreements to make mutations to data stored in a first data storage of a first type and second replicated state machines may execute the sequence of ordered agreements to make mutations to data stored in a second data storage of a second type. First metadata of the mutated data stored in the first data storage may then be received and stored, as may second metadata of the mutated data stored in the second data storage. The first and second metadata may be compared when the data stored in the first data storage that corresponds to the first metadata and the data stored in the second data storage that corresponds to the second metadata have settled according to the predetermined one of the sequence of ordered agreements. A selected action may then be carried out depending upon the comparison.

Methods, devices and systems for real-time checking of data consistency in a distributed heterogenous storage system

A computer-implemented method may comprise executing, by a first plurality of replicated state machines, a sequence of ordered agreements to make mutations to a data stored in a first data storage of a first type and executing, by a second plurality of replicated state machines, the sequence of ordered agreements to make mutations to the data stored in a second data storage of a second type. First metadata of the mutated data stored in the first data storage may then be received and stored, as may second metadata of the mutated data stored in the second data storage. A comparison of the stored first and second metadata may then be carried out when the data stored in the first data storage that corresponds to the first metadata and the data stored in the second data storage that corresponds to the second metadata have been determined to have settled according to the predetermined one of the sequence of ordered agreements. A selected action may then be carried out depending upon a result of the comparison.

A computer-implemented method may comprise receiving proposals to mutate a data stored in a distributed and replicated file system coupled to a network, the distributed and replicated data system comprising a plurality of nodes, each comprising a server. A metadata service maintains and updates a replica of a namespace of the distributed and replicated file system and coordinates updates to the data by generating an ordered set of agreements corresponding to the received proposals, the ordered set of agreements specifying an order in which the nodes are to mutate data stored in data nodes and cause corresponding changes to the state of the namespace. For each agreement in the generated ordered set of agreements, a corresponding writers list may be provided that comprises an ordered list of nodes to execute the agreement and make corresponding changes to the namespace. The ordered set of agreements may then be sent to the plurality of nodes along with, for each agreement in the ordered set of agreements, the corresponding writers list or a pre-generated index thereto and each of the plurality of nodes may be configured to only execute agreements for which it is a first-listed node on the received writers list.

Methods, devices and systems for writer pre-selection in distributed data systems

A cluster of nodes implements a single distributed file system comprises at least first and second data centers and a coordination engine process. The first data center may comprise first DataNodes configured to store data blocks of client files, and first NameNodes configured to update a state of a namespace of the cluster. The second data center, geographically remote from and coupled to the first data center by a wide area network, may comprise second DataNodes configured to store data blocks of client files, and second NameNodes configured to update the state of the namespace. The first and second NameNodes are configured to update the state of the namespace responsive to data blocks being written to the DataNodes. The coordination engine process spans the first and second NameNodes and coordinates updates to the namespace stored such that the state thereof is maintained consistent across the first and second data centers.

Geographically-distributed file system using coordinated namespace replication over a wide area network

A computer-implemented method of migrating metadata from a donor filesystem D having a rooted tree structure to a beneficiary filesystem B while processing commands that operate on the metadata may comprise, while a command to operate on the metadata is not received, replicating the donor filesystem D at the beneficiary filesystem B by sequentially copying metadata of nodes of the donor filesystem D to the beneficiary filesystem B. When a command is received to operate on the metadata, the command may be executed at both the donor filesystem D and the beneficiary filesystem B when all arguments of the command are present in both the donor filesystem D and the beneficiary filesystem B. When none of arguments are present in the beneficiary filesystem B, the command may be executed at the donor filesystem D only. When only some of the arguments are present in the beneficiary filesystem B, the command may be enqueued at least until all arguments of the command are present in the beneficiary filesystem B. When all arguments thereof are present in the beneficiary filesystem B, the enqueued commands may be dequeued and scheduled for execution.

Methods, devices and systems for migrating an active filesystem

A computer-implemented method may comprise providing a first executed agreement cache in a first data center and a second executed agreement cache in a second data center; receiving agreements on proposals to create or make changes to files stored in the first and second data centers; storing metadata of the files referred to by the received agreements the first and/or second executed agreement caches; maintaining the first and second executed agreement caches synchronous with one another before the files referred to by the received agreements are created or changed; creating or making changes to the file referred to by the received agreements only after the first and second executed agreement caches have been synchronized; and searching the first and/or second executed agreement caches for updated metadata whenever requests for data of files stored in the first or second data centers are received in the first or the second data centers and, responsive to the received requests, providing data corresponding to the updated metadata when updated metadata is found.

Methods, devices and systems for maintaining consistency of metadata and data across data centers

A first plurality of replicated state machines may execute a sequence of ordered agreements to make mutations to a data stored in a first data storage service of a first type. A second plurality of replicated state machines may execute the sequence of ordered agreements to make mutations to the data stored in a second data storage service of a second type. First metadata of the mutated data stored in the first data storage service may then be received and stored, and second metadata of the mutated data may be stored in the second data storage service. The stored first and second metadata may then be compared when the data have settled, and a selected action carried out based upon the result of the comparison.

A distributed system that implements an online exchange may comprise a plurality of server nodes, each of which being configured to receive exchange transaction proposals from customers of the online exchange over a computer network and each being configured to store a copy of a blockchain distributed ledger of completed exchange transactions. A consensus engine may be coupled, over the computer network, to the plurality of server nodes and may receive a plurality of exchange transaction proposals from the plurality of server nodes. The consensus engine may be being further configured to achieve consensus on the plurality of exchange transaction proposals and to generate, in response, an ordering of agreed-upon exchange transaction proposals that includes the plurality of exchange transaction proposals on which consensus has been reached. This ordering of agreed-upon exchange transaction proposals is identically provided to each of the server nodes and specifies the order in which the server nodes are to execute exchange transactions and to update their copy of the distributed ledger. The ordering of agreed-upon exchange transaction proposals may optionally be re-ordered and identically provided to each server node to conform to the local orderings at the exchange transaction proposal's node server of origin.

Methods, devices and systems for a distributed coordination engine-based exchange that implements a blockchain distributed ledger

A computer-implemented method and distributed system for maintaining consistency of client applications on a plurality of server nodes may comprise providing a first and second versions of a distributed coordination engine (DConE). The first version of the DConE may receive proposals, reach agreements thereon and generate a first ordering of agreements that specifies an order in which the client applications are to execute the agreed-upon proposals and correspondingly update their respective states. A ChangeVersion proposal may then be processed by the first version of the DConE, whereupon the first version of the DConE may stop reaching any further agreements. A second version of the DConE may then take over reaching agreements on the proposals and generate a second ordering of agreements, beginning with the agreed-upon ChangeVersion proposal. Any agreed-upon proposal, received from the first version of the DConE after the agreed-upon ChangeVersion proposal, may be sent back to the second version of the DConE to enable the second version of the DConE to reach agreement thereon.

Methods, devices and systems for non-disruptive upgrades to a replicated state machine in a distributed computing environment

A distributed system that implements an online exchange may comprise a plurality of server nodes, each of which being configured to receive exchange transaction proposals from customers of the online exchange over a computer network and each being configured to store a copy of a blockchain distributed ledger of completed exchange transactions. A distributed coordination engine may be coupled, over the computer network, to the plurality of server nodes and may receive a plurality of exchange transaction proposals from the plurality of server nodes. The distributed coordination engine may be being further configured to achieve consensus on the plurality of exchange transaction proposals and to generate, in response, an ordering of agreed-upon exchange transaction proposals that includes the plurality of exchange transaction proposals on which consensus has been reached. This ordering of agreed-upon exchange transaction proposals is identically provided to each of the server nodes and specifies the order in which the server nodes are to execute exchange transactions and to update their copy of the distributed ledger. The ordering of agreed-upon exchange transaction proposals may optionally be re-ordered and identically provided to each server node to conform to the local orderings at the exchange transaction proposal's node server of origin.

First and second pluralities of replicated state machines may execute a sequence of ordered agreements to make mutations to data stored in first and second data storage services of first and second types, respectively. First and second metadata of the mutated data stored in the first and second data storage services may then be received and stored. The first and second data storage services may then be synchronized using the received first and second metadata to determine when the data stored in the first and second data storage services have both settled after having mutated according to a predetermined agreement of the sequence of ordered agreements. A comparison of the stored first and second metadata may then be carried out when the data stored in the first data storage service and the data stored in the second data storage service have settled according to the predetermined agreement.

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Foster City, CA, United States of America

Yeturu Aahlad