1. A computer with a file system for managing storage of and access to a plurality of file system objects on a storage device, the plurality of file system objects including at least a first file and a second file, the first file and the second file each comprising one or more bytes of data stored on the storage device, comprising: storage configured to store data indicating whether integrity is applied to each of the file system objects, the integrity comprising performing a copy-on-write operation for write operations on a file system object; and a processing system comprising a memory and a processor, with computer program code stored in the memory that, when executed by the processing system, configures the processing system to respond to requests from applications to access file system objects on the storage, wherein access to one of the file system objects uses integrity in response to determining that the data indicates that integrity is applied to that file system object, and access to that file system object does not use integrity in response to determining that the data indicates that integrity is not applied to that file system object; the processing system being further configured by the computer program code to, in response to a request, change the data for the first file indicating whether integrity is applied to the first file.