US Patent 10002048 Point-in-time snap copy management in a deduplication environment

In accordance with one embodiment of the present description, a logical file unit containing a set of data stored in cache or other memory and mapped by a reference pointer to a physical file unit in a storage, may be overwritten with new data in the memory without first read/write copying the data in memory to a new logical file unit in the file system. Instead, the original physical file unit of data in the storage is preserved and the original reference pointer for the original physical file unit of data may be used to map a new logical file unit in the file system to the original physical file unit storing the original set of data. Other aspects are described.