A method comprising: invoking an interposed file system driver to request one or more operations on one or more logical files in a logical file system accessible via said interposed file system driver, wherein said logical file system is associated with logical file system metadata (181, 182, 186) that defines, at least in part, said logical file system, said logical file system metadata (181, 182, 186) including a metadata mapping between logical files in said logical file system and base files (170, 174) in a base file system, wherein said logical file system metadata (181, 182, 186) is stored in one or more specific base files of the base file system, wherein the logical file system metadata (181, 182, 186) of a particular logical file of said one or more logical files includes pointers to or offsets of each base data block (172A-172D, 176A-176C) of one or more particular base files (170, 174) mapped, by the metadata mapping, to the particular logical file; performing the one or more operations, wherein performing the one or more operations includes: accessing said metadata mapping to determine that one or more particular base files (170, 174) are mapped to the particular logical file; using at least one of said pointers or offsets included in the logical file system metadata (181, 182, 186) of the particular logical file to access at least one base data block (172A-172D, 176A- 176C of said one or more particular base files (170, 174) determined to be mapped to said particular logical file; and wherein the method is performed on one or more computing devices. invoking an interposed file system driver to request one or more operations on one or more logical files in a logical file system accessible via said interposed file system driver, wherein said logical file system is associated with logical file system metadata (181, 182, 186) that defines, at least in part, said logical file system, said logical file system metadata (181, 182, 186) including a metadata mapping between logical files in said logical file system and base files (170, 174) in a base file system, wherein said logical file system metadata (181, 182, 186) is stored in one or more specific base files of the base file system, wherein the logical file system metadata (181, 182, 186) of a particular logical file of said one or more logical files includes pointers to or offsets of each base data block (172A-172D, 176A-176C) of one or more particular base files (170, 174) mapped, by the metadata mapping, to the particular logical file; performing the one or more operations, wherein performing the one or more operations includes: accessing said metadata mapping to determine that one or more particular base files (170, 174) are mapped to the particular logical file; using at least one of said pointers or offsets included in the logical file system metadata (181, 182, 186) of the particular logical file to access at least one base data block (172A-172D, 176A- 176C of said one or more particular base files (170, 174) determined to be mapped to said particular logical file; and accessing said metadata mapping to determine that one or more particular base files (170, 174) are mapped to the particular logical file; using at least one of said pointers or offsets included in the logical file system metadata (181, 182, 186) of the particular logical file to access at least one base data block (172A-172D, 176A- 176C of said one or more particular base files (170, 174) determined to be mapped to said particular logical file; and wherein the method is performed on one or more computing devices.