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diff --git a/Documentation/filesystems/ntfs.rst b/Documentation/filesystems/ntfs.rst deleted file mode 100644 index 5bb093a26485..000000000000 --- a/Documentation/filesystems/ntfs.rst +++ /dev/null @@ -1,466 +0,0 @@ -.. 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. |