Abstract: A method of providing on-demand service through a virtual file system is implemented at a computing device. In response to receiving a request for a file associated with an instance of the virtual file system, the computing device checks the metadata of the requested file in the virtual file system to identify a first set of data blocks of the requested file that is not present at the computing device and retrieves the first set of data blocks from at least one of a plurality of storage devices associated with the virtual file system. The computing device generates a copy of the requested file using the retrieved first set of data blocks and returns the generated copy of the requested file to the requesting application or user.

Abstract: A method of synchronizing a virtual file system is implemented at a computing device. The virtual file system has a hierarchical tree structure including a plurality of tree nodes, each tree node having associated metadata and corresponding to a respective component of the virtual file system. Upon receipt of a request to generate a revision of a virtual file system in at least one storage device, the computing device serializes each tree node's associated metadata into an object, generates an object ID from the serialized object, and stores the object in the storage device if the object ID is not found in an object-storage mapping table associated with the virtual file system. Finally, the computing device inserts the object ID into the object-storage mapping table and stores the object-storage mapping table in the storage device after processing the last tree node.

Abstract: A method of recovering information missing from a virtual file system is implemented at a computing device that is communicatively connected to one or more storage devices. Upon receipt of a request for a file associated with an instance of the virtual file system, the computing device retrieves a set of blocks associated with the file from one of the storage devices and identifies one or more of the set of blocks as missing blocks after failing to retrieve the missing blocks from the storage devices. For each missing block, the computing device retrieves one or more parity blocks from one of the storage devices and computes the missing block by applying a predefined recovery scheme to the retrieved parity blocks. Finally, the computing device reconstructs the requested file using the computed missing blocks and other blocks associated with the requested file.

Abstract: A method of resolving conflicts between revisions to a distributed virtual file system is implemented at a computing device that is communicatively connected to a plurality of storage devices. The virtual file system at the computing device has a first revision of the virtual file system. Upon receipt of a request to synchronize the first revision of the virtual file system with the storage devices, the computing device retrieves one or more blocks from the storage devices, which are associated with a second revision of the virtual file system. The computing device then merges a first component of the first revision with a corresponding component of the second revision if a first predefined condition is met or identifies a second component of the first revision as being conflicted with a corresponding component of the second revision if a second predefined set of conditions is met.

Abstract: A method for forming a virtual file system associated with a distributed storage system is implemented at a computing device communicatively connected to the distributed storage system. The computing device retrieves one or more metadata blocks associated with the virtual file system from the plurality of storage devices. After rendering a commit tree for the virtual file system, the computing device builds an instance of the virtual file system by traversing a plurality of directory nodes and file nodes associated with the tree in a recursive manner. For a respective directory node, the computing device creates a directory in accordance with the metadata associated with the directory node; for a respective file node, the computing device retrieves one or more data blocks from the plurality of storage devices in accordance with the metadata associated with the file node and creates a file using the retrieved data blocks.

Abstract: A method for forming a virtual file system associated with a distributed storage system is implemented at a computing device communicatively connected to the distributed storage system. The computing device retrieves one or more metadata blocks associated with the virtual file system from the plurality of storage devices. After rendering a commit tree for the virtual file system, the computing device builds an instance of the virtual file system by traversing a plurality of directory nodes and file nodes associated with the tree in a recursive manner. For a respective directory node, the computing device creates a directory in accordance with the metadata associated with the directory node; for a respective file node, the computing device retrieves one or more data blocks from the plurality of storage devices in accordance with the metadata associated with the file node and creates a file using the retrieved data blocks.