mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 10:04:12 +08:00
461f2c8f13
- Add a SPDX header; - Adjust document title; - Comment out text-only ToC; - Some whitespace fixes and new line breaks; - Mark literal blocks as such; - Add table markups; - Add it to filesystems/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/f09ca6c9bdd4e7aa7208f3dba0b8753080b38d03.1581955849.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
467 lines
20 KiB
ReStructuredText
467 lines
20 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
================================
|
|
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 values can be used for "opt":
|
|
|
|
======== =========================================
|
|
continue DEFAULT, try to clean-up as much as
|
|
possible, e.g. marking a corrupt inode as
|
|
bad so it is no longer accessed, and then
|
|
continue.
|
|
recover At present only supported is recovery of
|
|
the boot sector from the backup copy.
|
|
If read-only mount, the recovery is done
|
|
in memory only and not written to disk.
|
|
======== =========================================
|
|
|
|
Note that the options are additive, i.e. specifying::
|
|
|
|
errors=continue,errors=recover
|
|
|
|
means the driver will attempt to recover and if that
|
|
fails it will clean-up as much as possible and
|
|
continue.
|
|
|
|
mft_zone_multiplier= Set the MFT zone multiplier for the volume (this
|
|
setting is not persistent across mounts and can be
|
|
changed from mount to mount but cannot be changed on
|
|
remount). Values of 1 to 4 are allowed, 1 being the
|
|
default. The MFT zone multiplier determines how much
|
|
space is reserved for the MFT on the volume. If all
|
|
other space is used up, then the MFT zone will be
|
|
shrunk dynamically, so this has no impact on the
|
|
amount of free space. However, it can have an impact
|
|
on performance by affecting fragmentation of the MFT.
|
|
In general use the default. If you have a lot of small
|
|
files then use a higher value. The values have the
|
|
following meaning:
|
|
|
|
===== =================================
|
|
Value MFT zone size (% of volume size)
|
|
===== =================================
|
|
1 12.5%
|
|
2 25%
|
|
3 37.5%
|
|
4 50%
|
|
===== =================================
|
|
|
|
Note this option is irrelevant for read-only mounts.
|
|
======================= =======================================================
|
|
|
|
|
|
Known bugs and (mis-)features
|
|
=============================
|
|
|
|
- The link count on each directory inode entry is set to 1, due to Linux not
|
|
supporting directory hard links. This may well confuse some user space
|
|
applications, since the directory names will have the same inode numbers.
|
|
This also speeds up ntfs_read_inode() immensely. And we haven't found any
|
|
problems with this approach so far. If you find a problem with this, please
|
|
let us know.
|
|
|
|
|
|
Please send bug reports/comments/feedback/abuse to the Linux-NTFS development
|
|
list at sourceforge: linux-ntfs-dev@lists.sourceforge.net
|
|
|
|
|
|
Using NTFS volume and stripe sets
|
|
=================================
|
|
|
|
For support of volume and stripe sets, you can either use the kernel's
|
|
Device-Mapper driver or the kernel's Software RAID / MD driver. The former is
|
|
the recommended one to use for linear raid. But the latter is required for
|
|
raid level 5. For striping and mirroring, either driver should work fine.
|
|
|
|
|
|
The Device-Mapper driver
|
|
------------------------
|
|
|
|
You will need to create a table of the components of the volume/stripe set and
|
|
how they fit together and load this into the kernel using the dmsetup utility
|
|
(see man 8 dmsetup).
|
|
|
|
Linear volume sets, i.e. linear raid, has been tested and works fine. Even
|
|
though untested, there is no reason why stripe sets, i.e. raid level 0, and
|
|
mirrors, i.e. raid level 1 should not work, too. Stripes with parity, i.e.
|
|
raid level 5, unfortunately cannot work yet because the current version of the
|
|
Device-Mapper driver does not support raid level 5. You may be able to use the
|
|
Software RAID / MD driver for raid level 5, see the next section for details.
|
|
|
|
To create the table describing your volume you will need to know each of its
|
|
components and their sizes in sectors, i.e. multiples of 512-byte blocks.
|
|
|
|
For NT4 fault tolerant volumes you can obtain the sizes using fdisk. So for
|
|
example if one of your partitions is /dev/hda2 you would do::
|
|
|
|
$ fdisk -ul /dev/hda
|
|
|
|
Disk /dev/hda: 81.9 GB, 81964302336 bytes
|
|
255 heads, 63 sectors/track, 9964 cylinders, total 160086528 sectors
|
|
Units = sectors of 1 * 512 = 512 bytes
|
|
|
|
Device Boot Start End Blocks Id System
|
|
/dev/hda1 * 63 4209029 2104483+ 83 Linux
|
|
/dev/hda2 4209030 37768814 16779892+ 86 NTFS
|
|
/dev/hda3 37768815 46170809 4200997+ 83 Linux
|
|
|
|
And you would know that /dev/hda2 has a size of 37768814 - 4209030 + 1 =
|
|
33559785 sectors.
|
|
|
|
For Win2k and later dynamic disks, you can for example use the ldminfo utility
|
|
which is part of the Linux LDM tools (the latest version at the time of
|
|
writing is linux-ldm-0.0.8.tar.bz2). You can download it from:
|
|
|
|
http://www.linux-ntfs.org/
|
|
|
|
Simply extract the downloaded archive (tar xvjf linux-ldm-0.0.8.tar.bz2), go
|
|
into it (cd linux-ldm-0.0.8) and change to the test directory (cd test). You
|
|
will find the precompiled (i386) ldminfo utility there. NOTE: You will not be
|
|
able to compile this yourself easily so use the binary version!
|
|
|
|
Then you would use ldminfo in dump mode to obtain the necessary information::
|
|
|
|
$ ./ldminfo --dump /dev/hda
|
|
|
|
This would dump the LDM database found on /dev/hda which describes all of your
|
|
dynamic disks and all the volumes on them. At the bottom you will see the
|
|
VOLUME DEFINITIONS section which is all you really need. You may need to look
|
|
further above to determine which of the disks in the volume definitions is
|
|
which device in Linux. Hint: Run ldminfo on each of your dynamic disks and
|
|
look at the Disk Id close to the top of the output for each (the PRIVATE HEADER
|
|
section). You can then find these Disk Ids in the VBLK DATABASE section in the
|
|
<Disk> components where you will get the LDM Name for the disk that is found in
|
|
the VOLUME DEFINITIONS section.
|
|
|
|
Note you will also need to enable the LDM driver in the Linux kernel. If your
|
|
distribution did not enable it, you will need to recompile the kernel with it
|
|
enabled. This will create the LDM partitions on each device at boot time. You
|
|
would then use those devices (for /dev/hda they would be /dev/hda1, 2, 3, etc)
|
|
in the Device-Mapper table.
|
|
|
|
You can also bypass using the LDM driver by using the main device (e.g.
|
|
/dev/hda) and then using the offsets of the LDM partitions into this device as
|
|
the "Start sector of device" when creating the table. Once again ldminfo would
|
|
give you the correct information to do this.
|
|
|
|
Assuming you know all your devices and their sizes things are easy.
|
|
|
|
For a linear raid the table would look like this (note all values are in
|
|
512-byte sectors)::
|
|
|
|
# Offset into Size of this Raid type Device Start sector
|
|
# volume device of device
|
|
0 1028161 linear /dev/hda1 0
|
|
1028161 3903762 linear /dev/hdb2 0
|
|
4931923 2103211 linear /dev/hdc1 0
|
|
|
|
For a striped volume, i.e. raid level 0, you will need to know the chunk size
|
|
you used when creating the volume. Windows uses 64kiB as the default, so it
|
|
will probably be this unless you changes the defaults when creating the array.
|
|
|
|
For a raid level 0 the table would look like this (note all values are in
|
|
512-byte sectors)::
|
|
|
|
# Offset Size Raid Number Chunk 1st Start 2nd Start
|
|
# into of the type of size Device in Device in
|
|
# volume volume stripes device device
|
|
0 2056320 striped 2 128 /dev/hda1 0 /dev/hdb1 0
|
|
|
|
If there are more than two devices, just add each of them to the end of the
|
|
line.
|
|
|
|
Finally, for a mirrored volume, i.e. raid level 1, the table would look like
|
|
this (note all values are in 512-byte sectors)::
|
|
|
|
# Ofs Size Raid Log Number Region Should Number Source Start Target Start
|
|
# in of the type type of log size sync? of Device in Device in
|
|
# vol volume params mirrors Device Device
|
|
0 2056320 mirror core 2 16 nosync 2 /dev/hda1 0 /dev/hdb1 0
|
|
|
|
If you are mirroring to multiple devices you can specify further targets at the
|
|
end of the line.
|
|
|
|
Note the "Should sync?" parameter "nosync" means that the two mirrors are
|
|
already in sync which will be the case on a clean shutdown of Windows. If the
|
|
mirrors are not clean, you can specify the "sync" option instead of "nosync"
|
|
and the Device-Mapper driver will then copy the entirety of the "Source Device"
|
|
to the "Target Device" or if you specified multiple target devices to all of
|
|
them.
|
|
|
|
Once you have your table, save it in a file somewhere (e.g. /etc/ntfsvolume1),
|
|
and hand it over to dmsetup to work with, like so::
|
|
|
|
$ dmsetup create myvolume1 /etc/ntfsvolume1
|
|
|
|
You can obviously replace "myvolume1" with whatever name you like.
|
|
|
|
If it all worked, you will now have the device /dev/device-mapper/myvolume1
|
|
which you can then just use as an argument to the mount command as usual to
|
|
mount the ntfs volume. For example::
|
|
|
|
$ mount -t ntfs -o ro /dev/device-mapper/myvolume1 /mnt/myvol1
|
|
|
|
(You need to create the directory /mnt/myvol1 first and of course you can use
|
|
anything you like instead of /mnt/myvol1 as long as it is an existing
|
|
directory.)
|
|
|
|
It is advisable to do the mount read-only to see if the volume has been setup
|
|
correctly to avoid the possibility of causing damage to the data on the ntfs
|
|
volume.
|
|
|
|
|
|
The Software RAID / MD driver
|
|
-----------------------------
|
|
|
|
An alternative to using the Device-Mapper driver is to use the kernel's
|
|
Software RAID / MD driver. For which you need to set up your /etc/raidtab
|
|
appropriately (see man 5 raidtab).
|
|
|
|
Linear volume sets, i.e. linear raid, as well as stripe sets, i.e. raid level
|
|
0, have been tested and work fine (though see section "Limitations when using
|
|
the MD driver with NTFS volumes" especially if you want to use linear raid).
|
|
Even though untested, there is no reason why mirrors, i.e. raid level 1, and
|
|
stripes with parity, i.e. raid level 5, should not work, too.
|
|
|
|
You have to use the "persistent-superblock 0" option for each raid-disk in the
|
|
NTFS volume/stripe you are configuring in /etc/raidtab as the persistent
|
|
superblock used by the MD driver would damage the NTFS volume.
|
|
|
|
Windows by default uses a stripe chunk size of 64k, so you probably want the
|
|
"chunk-size 64k" option for each raid-disk, too.
|
|
|
|
For example, if you have a stripe set consisting of two partitions /dev/hda5
|
|
and /dev/hdb1 your /etc/raidtab would look like this::
|
|
|
|
raiddev /dev/md0
|
|
raid-level 0
|
|
nr-raid-disks 2
|
|
nr-spare-disks 0
|
|
persistent-superblock 0
|
|
chunk-size 64k
|
|
device /dev/hda5
|
|
raid-disk 0
|
|
device /dev/hdb1
|
|
raid-disk 1
|
|
|
|
For linear raid, just change the raid-level above to "raid-level linear", for
|
|
mirrors, change it to "raid-level 1", and for stripe sets with parity, change
|
|
it to "raid-level 5".
|
|
|
|
Note for stripe sets with parity you will also need to tell the MD driver
|
|
which parity algorithm to use by specifying the option "parity-algorithm
|
|
which", where you need to replace "which" with the name of the algorithm to
|
|
use (see man 5 raidtab for available algorithms) and you will have to try the
|
|
different available algorithms until you find one that works. Make sure you
|
|
are working read-only when playing with this as you may damage your data
|
|
otherwise. If you find which algorithm works please let us know (email the
|
|
linux-ntfs developers list linux-ntfs-dev@lists.sourceforge.net or drop in on
|
|
IRC in channel #ntfs on the irc.freenode.net network) so we can update this
|
|
documentation.
|
|
|
|
Once the raidtab is setup, run for example raid0run -a to start all devices or
|
|
raid0run /dev/md0 to start a particular md device, in this case /dev/md0.
|
|
|
|
Then just use the mount command as usual to mount the ntfs volume using for
|
|
example::
|
|
|
|
mount -t ntfs -o ro /dev/md0 /mnt/myntfsvolume
|
|
|
|
It is advisable to do the mount read-only to see if the md volume has been
|
|
setup correctly to avoid the possibility of causing damage to the data on the
|
|
ntfs volume.
|
|
|
|
|
|
Limitations when using the Software RAID / MD driver
|
|
-----------------------------------------------------
|
|
|
|
Using the md driver will not work properly if any of your NTFS partitions have
|
|
an odd number of sectors. This is especially important for linear raid as all
|
|
data after the first partition with an odd number of sectors will be offset by
|
|
one or more sectors so if you mount such a partition with write support you
|
|
will cause massive damage to the data on the volume which will only become
|
|
apparent when you try to use the volume again under Windows.
|
|
|
|
So when using linear raid, make sure that all your partitions have an even
|
|
number of sectors BEFORE attempting to use it. You have been warned!
|
|
|
|
Even better is to simply use the Device-Mapper for linear raid and then you do
|
|
not have this problem with odd numbers of sectors.
|