In one embodiment of file integrity preservation in accordance with the present description, a file is subdivided into a plurality of subfiles, and a write update originally targeted for a portion of that file contained within one of the subfiles, is instead directed to a temporary copy subfile. As a consequence, the temporary copy subfile which is updated with the write data, may be scanned for viruses or other malware separately from the original file and its corresponding original subfile. If the temporary copy subfile passes the scanning test, the originally targeted file may be updated with the updated contents of the clean temporary copy subfile. Conversely, in the event that the write update introduced malicious software to the temporary copy subfile, the original file and its corresponding original subfile remain uncontaminated by the write update. Other aspects are also described.