docs: filesystems: convert ntfs.txt to ReST

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.. SPDX-License-Identifier: GPL-2.0

================================

The Linux NTFS filesystem driver

================================

Table of contents

=================

.. Table of contents

   - Overview

   - Web site

  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:

- 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

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.

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

			  ========  =========================================

			  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

			  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:

			  ========  =========================================

			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.

			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

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:

example if one of your partitions is /dev/hda2 you would do::

    $ fdisk -ul /dev/hda

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:

Then you would use ldminfo in dump mode to obtain the necessary information::

    $ ./ldminfo --dump /dev/hda

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):

512-byte sectors)::

--- cut here ---

    # 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

--- cut here ---

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):

512-byte sectors)::

--- cut here ---

    # 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

--- cut here ---

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):

this (note all values are in 512-byte sectors)::

--- cut here ---

    # 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

--- cut here ---

If you are mirroring to multiple devices you can specify further targets at the

end of the line.

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:

and hand it over to dmsetup to work with, like so::

    $ dmsetup create myvolume1 /etc/ntfsvolume1

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 the ntfs volume.  For example::

    $ mount -t ntfs -o ro /dev/device-mapper/myvolume1 /mnt/myvol1

"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:

and /dev/hdb1 your /etc/raidtab would look like this::

    raiddev /dev/md0

	    raid-level	0

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

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