Abstract: Systems and methods are provided herein for efficient local caching of data tiered to cloud storage to help reduce the bandwidth cost of repeated reads and writes to the same region of a stubbed file, increase the performance of write operations, and increase performance of read operations to portions of a stubbed file accessed repeatedly. When operations are directed toward data tiered to the cloud, the data can be read from cloud storage and stored within a local cache. A cache tracking tree can be generated and used to track file regions of a stub file, cached states associated with regions of the stub file, a set of cache flags, and other file and mapping data. For example, the cache state of regions of a stub file can be tracked including a cached data state, a non-cached state, a modified state, or a truncated state.

Abstract: Systems and methods are provided herein for establishing data constructs necessary for efficient and transparent tiering of data from local storage to cloud storage, and there use in transferring data to and from cloud storage. Files data can split into chunks and stored as individual objects in cloud storage. A stub file can replace the local file in local storage and describe a mapping of cloud objects that contain data to specific regions of the file. Upon creation of the stub and transfer of data to cloud storage, local storage capacity previously dedicated to file data can be freed for other uses.

Abstract: Systems and methods are provided herein for writing back data to files tiered in cloud storage. Files tiered to cloud storage can be stored in chunks where each chunk is stored as a distinct cloud object and where each cloud object is mapped to known offset regions of a file and the mapping is stored in local storage within a stub file. If the file is modified locally, e.g., a write has occurred, the offset range associated with the write can be used to determine which cloud object associated with the file is being modified. A new cloud object can be stored with the write data, while the previous cloud object is retained in cloud storage. The mapping, stored within the stub file can updated to reference the new cloud object for the region of the file that was modified. In addition, mapping can be retained for the previous version of the file allowing for efficient recall of past versions of files.