FS I/O Controls (Compact 2013)

3/26/2014

The following table shows the file system I/O controls with a description of each.

I/O Control	Description
FSCTL_GET_COMPRESSION	Obtains the current compression state of a file or directory on a volume whose file system supports per-stream compression.
FSCTL_GET_REGISTRY_INFO	Obtains information about a registry key.
FSCTL_QUERY_ALLOCATED_RANGES	Scans a file or alternate stream, looking for ranges that contain nonzero data. Only compressed or sparse files can have ranges set to zero known to the OS. For other files, the output buffer contains only a single entry that contains the starting point and the length requested.
FSCTL_SET_COMPRESSION	Sets the compression state of a file or directory on a volume whose file system supports per-file and per-directory compression. You can use this I/O control to compress or decompress a file or directory on such a volume.
FSCTL_SET_EXTENDED_FLAGS	Sets the extended flags on a file.
FSCTL_SET_SPARSE	Marks the specified file as sparse. In a sparse file, large ranges of zeros may not require disk allocation. Space for nonzero data is allocated as needed as the file is written.
FSCTL_SET_ZERO_DATA	Fills a specified range of a file with zeros.
FSCTL_USER	Can be be used to define additional file system driver FSD I/O controls.
FSSCTL_FLUSH_BUFFERS	Flushes all buffers on a specified file system.

See Also