Abstract: A method of data sharing among multiple entities is provided. Each entity exports to a data store a structured data representation comprising a versioned file system local to that entity. The method begins by forming a sharing group that includes two or more entities. Sharing of the structured data representations by members of the sharing group is enabled. The filers use a single distributed lock to protect each version of the file system. This lock is managed to allow each filer access to the shared file system volume to create its new version. To share a fully-versioned file system, asynchronous updates at each of the filers is permitted, and each node is then allowed to “push” its individual changes to the store to form the next version of the file system. A mechanism also may be used to reduce the period during which filers in the group operate under lock.

Abstract: A versioned file system comprises a set of structured data representations, such as XML. Each structured data representation corresponds to a “version,” and each version comprises a tree of write-once objects rooted at a root directory manifest. Each version in the versioned file system has associated therewith a “borrow window.” When it is desired to reconstruct the file system to a point in time (or, more generally, a given state), i.e., to perform a “restore,” it is only required to walk (use) a single structured data representation (a tree). During a restore, metadata is pulled back from the cloud first, so users can see the existence of needed files immediately. The remainder of the data is then pulled back from the cloud if/when the user goes to open the file. As a result, the entire file system (or any portion thereof) can be restored to a previous time nearly instantaneously.

Abstract: A versioned file system comprises a set of structured data representations, such as XML. Each structured data representation corresponds to a “version,” and each version comprises a tree of write-once objects rooted at a root directory manifest. Each version in the versioned file system has associated therewith a “borrow window.” When it is desired to reconstruct the file system to a point in time (or, more generally, a given state), i.e., to perform a “restore,” it is only required to walk (use) a single structured data representation (a tree). During a restore, metadata is pulled back from the cloud first, so users can see the existence of needed files immediately. The remainder of the data is then pulled back from the cloud if/when the user goes to open the file. As a result, the entire file system (or any portion thereof) can be restored to a previous time nearly instantaneously.

Abstract: A versioned file system comprises a set of structured data representations, such as XML. In a representative embodiment, at a first time, the interface creates and exports to the data store a first structured data representation corresponding to a first version of the local file system. The first structured data representation is an XML tree having a root element, one or more directory elements associated with the root element, and one or more file elements associated with a given directory element. Upon a change within the file system (e.g., file creation, file deletion, file modification, directory creation, directory deletion and directory modification), the interface creates and exports a second structured data representation corresponding to a second version of the file system. The second structured data representation differs from the first structured data representation up to and including the root element of the second structured data representation.

Abstract: An interface between an existing local file system and a data store (e.g., a “write-once” store) generates and exports to the data store a “versioned” file system. The state of the local file system at a given point in time can be determined using the versioned file system. Preferably, the versioned file system comprises a set of structured data representations (such as XML) that comprise metadata associated with the actual file system data. In operation, the interface creates and exports to the data store structured data representations, which correspond to versions of the local file system, as well as the actual file system data that these structured data representations represent. A cache associated with the interface stores recently used data and metadata, as well as all write data and metadata waiting to be transferred to the data store. Prior to transfer, one or more data transformations, such as compression, encryption, de-duplication and the like, may be applied to the data and metadata.