The Linux NTFS filesystem driver
================================
Table of contents
=================
- Overview
- Web site
- Features
- Supported mount options
- Known bugs and (mis-)features
- Using NTFS volume and stripe sets
- The Device-Mapper driver
- The Software RAID / MD driver
- Limitations when using the MD driver
Overview
========
Linux-NTFS comes with a number of user-space programs known as ntfsprogs.
These include mkntfs, a full-featured ntfs filesystem format utility,
ntfsundelete used for recovering files that were unintentionally deleted
from an NTFS volume and ntfsresize which is used to resize an NTFS partition.
See the web site for more information.
To mount an NTFS 1.2/3.x (Windows NT4/2000/XP/2003) volume, use the file
system type 'ntfs'. The driver currently supports read-only mode (with no
fault-tolerance, encryption or journalling) and very limited, but safe, write
support.
For fault tolerance and raid support (i.e. volume and stripe sets), you can
use the kernel's Software RAID / MD driver. See section "Using Software RAID
with NTFS" for details.
Web site
========
There is plenty of additional information on the linux-ntfs web site
at http://www.linux-ntfs.org/
The web site has a lot of additional information, such as a comprehensive
FAQ, documentation on the NTFS on-disk format, information on the Linux-NTFS
userspace utilities, etc.
Features
========
- This is a complete rewrite of the NTFS driver that used to be in the 2.4 and
earlier kernels. This new driver implements NTFS read support and is
functionally equivalent to the old ntfs driver and it also implements limited
write support. The biggest limitation at present is that files/directories
cannot be created or deleted. See below for the list of write features that
are so far supported. Another limitation is that writing to compressed files
is not implemented at all. Also, neither read nor write access to encrypted
files is so far implemented.
- The new driver has full support for sparse files on NTFS 3.x volumes which
the old driver isn't happy with.
- The new driver supports execution of binaries due to mmap() now being
supported.
- The new driver supports loopback mounting of files on NTFS which is used by
some Linux distributions to enable the user to run Linux from an NTFS
partition by creating a large file while in Windows and then loopback
mounting the file while in Linux and creating a Linux filesystem on it that
is used to install Linux on it.
- A comparison of the two drivers using:
time find . -type f -exec md5sum "{}" \;
run three times in sequence with each driver (after a reboot) on a 1.4GiB
NTFS partition, showed the new driver to be 20% faster in total time elapsed
(from 9:43 minutes on average down to 7:53). The time spent in user space
was unchanged but the time spent in the kernel was decreased by a factor of
2.5 (from 85 CPU seconds down to 33).
- The driver does not support short file names in general. For backwards
compatibility, we implement access to files using their short file names if
they exist. The driver will not create short file names however, and a
rename will discard any existing short file name.
- The new driver supports exporting of mounted NTFS volumes via NFS.
- The new driver supports async io (aio).
- The new driver supports fsync(2), fdatasync(2), and msync(2).
- The new driver supports readv(2) and writev(2).
- The new driver supports access time updates (including mtime and ctime).
- The new driver supports truncate(2) and open(2) with O_TRUNC. But at present
only very limited support for highly fragmented files, i.e. ones which have
their data attribute split across multiple extents, is included. Another
limitation is that at present truncate(2) will never create sparse files,
since to mark a file sparse we need to modify the directory entry for the
file and we do not implement directory modifications yet.
- The new driver supports write(2) which can both overwrite existing data and
extend the file size so that you can write beyond the existing data. Also,
writing into sparse regions is supported and the holes are filled in with
clusters. But at present only limited support for highly fragmented files,
i.e. ones which have their data attribute split across multiple extents, is
included. Another limitation is that write(2) will never create sparse
files, since to mark a file sparse we need to modify the directory entry for
the file and we do not implement directory modifications yet.
Supported mount options
=======================
In addition to the generic mount options described by the manual page for the
mount command (man 8 mount, also see man 5 fstab), the NTFS driver supports the
following mount options:
iocharset=name Deprecated option. Still supported but please use
nls=name in the future. See description for nls=name.
nls=name Character set to use when returning file names.
Unlike VFAT, NTFS suppresses names that contain
unconvertible characters. Note that most character
sets contain insufficient characters to represent all
possible Unicode characters that can exist on NTFS.
To be sure you are not missing any files, you are
advised to use nls=utf8 which is capable of
representing all Unicode characters.
utf8=<bool> Option no longer supported. Currently mapped to
nls=utf8 but please use nls=utf8 in the future and
make sure utf8 is compiled either as module or into
the kernel. See description for nls=name.
uid=
gid=
umask= Provide default owner, group, and access mode mask.
These options work as documented in mount(8). By
default, the files/directories are owned by root and
he/she has read and write permissions, as well as
browse permission for directories. No one else has any
access permissions. I.e. the mode on all files is by
default rw------- and for directories rwx------, a
consequence of the default fmask=0177 and dmask=0077.
Using a umask of zero will grant all permissions to
everyone, i.e. all files and directories will have mode
rwxrwxrwx.
fmask=
dmask= Instead of specifying umask which applies both to
files and directories, fmask applies only to files and
dmask only to directories.
sloppy=<BOOL> If sloppy is specified, ignore unknown mount options.
Otherwise the default behaviour is to abort mount if
any unknown options are found.
show_sys_files=<BOOL> If show_sys_files is specified, show the system files
in directory listings. Otherwise the default behaviour
is to hide the system files.
Note that even when show_sys_files is specified, "$MFT"
will not be visible due to bugs/mis-features in glibc.
Further, note that irrespective of show_sys_files, all
files are accessible by name, i.e. you can always do
"ls -l \$UpCase" for example to specifically show the
system file containing the Unicode upcase table.
case_sensitive=<BOOL> If case_sensitive is specified, treat all file names as
case sensitive and create file names in the POSIX
namespace. Otherwise the default behaviour is to treat
file names as case insensitive and to create file names
in the WIN32/LONG name space. Note, the Linux NTFS
driver will never create short file names and will
remove them on rename/delete of the corresponding long
file name.
Note that files remain accessible via their short file
name, if it exists. If case_sensitive, you will need
to provide the correct case of the short file name.
disable_sparse=<BOOL> If disable_sparse is specified, creation of sparse
regions, i.e. holes, inside files is disabled for the
volume (for the duration of this mount only). By
default, creation of sparse regions is enabled, which
is consistent with the behaviour of traditional Unix
filesystems.
errors=opt What to do when critical filesystem errors are found.
Following value
