Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.