fsutil
Updated: January 21, 2005
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Fsutil is a command-line utility that you can use to
perform many tasks related to file allocation table (FAT) and
NTFS file systems, such as managing reparse points, managing
sparse files, or dismounting a volume. Because fsutil is
quite powerful, it should only be used by advanced users who
have a thorough knowledge of Windows XPor the Windows
Server 2003 family of operating systems. In addition, you must
be logged on as an administrator or a member of the
Administrators group in order to use fsutil.
The following table lists the fsutil subcommands.
| Command | Description |
| Fsutil: behavior | Queries, changes, enables, or disables the settings for generating 8.3 character-length file names, accepting extended characters in 8.3 character-length file names on NTFS volumes, updating the last access timestamp on NTFS volumes, how often quota events are written to the system log, the internal cache levels of NTFS paged pool and NTFS non-paged pool memory, and the amount of disk space reserved for the MFT Zone. |
| Fsutil: dirty | Queries whether volume's dirty bit is set. Sets a volume's dirty bit. When a volume's dirty bit is set, autochk automatically checks the volume for errors the next time the computer is restarted. |
| Fsutil: file | Typically used by support professionals. Finds a file by user name (if Disk Quotas are enabled), queries allocated ranges for a file, sets a file's short name, sets a file's valid data length, or sets zero data for a file. |
| Fsutil: fsinfo | Typically used by support professionals. Lists all drives, queries the drive type, queries volume information, queries NTFS-specific volume information, or queries file system statistics. |
| Fsutil: hardlink | Creates a hard link. A hard link is a directory entry for a file. Every file can be considered to have at least one hard link. On NTFS volumes, each file can have multiple hard links, and thus a single file can appear in many directories (or even in the same directory with different names). Because all of the links reference the same file, programs can open any of the links and modify the file. A file is deleted from the file system only after all links to it have been deleted. After you create a hard link, programs can use it like any other file name. |
| Fsutil: objectid | Typically used by support professionals. Manages object identifiers, which are used by Windows XPand the Windows Server 2003 family of operating systems to track objects such as files and directories. |
| Fsutil: quota | Manages disk quotas on NTFS volumes in order to provide more precise control of network-based storage. Disk quotas are implemented on a per-volume basis and enable both hard- and soft-storage limits to be implemented on a per-user basis. |
| Fsutil: reparsepoint | Typically used by support professionals. Queries or deletes reparse points, which are NTFS file system objects that have a definable attribute containing user-controlled data, and are used to extend functionality in the input/output (I/O) subsystem. Reparse points are used for directory junction points and volume mount points. They are also used by file system filter drivers to mark certain files as special to that driver. |
| Fsutil: sparse | Manages sparse files. A sparse file is a file with one or more regions of unallocated data in it. A program will see these unallocated regions as containing bytes with the value zero, but there is actually no disk space used to represent these zeros. In other words, all meaningful or nonzero data is allocated, whereas all non-meaningful data (large strings of data composed of zeros) is not allocated. When a sparse file is read, allocated data is returned as stored and unallocated data is returned, by default, as zeros, in accordance with the C2 security requirement specification. Sparse file support allows data to be deallocated from anywhere in the file. |
| Fsutil: usn | Typically used by support professionals. Manages the update sequence number (USN) change journal, which provides a persistent log of all changes made to files on the volume. |
| Fsutil: volume | Manages a volume. Dismounts a volume or queries to see how much free space is available on a disk. |
Formatting legend
| Format | Meaning |
| Italic | Information that the user must supply |
| Bold | Elements that the user must type exactly as shown |
| Ellipsis (...) | Parameter that can be repeated several times in a command line |
| Between brackets ([]) | Optional items |
| Between braces ({}); choices separated by pipe (|). Example: {even|odd} | Set of choices from which the user must choose only one |
| Courier font | Code or program output |