The Linux NTFS filesystem driver ================================ Table of contents ================= - Overview - Supported mount options - Features - Known bugs and (mis-)features - Using Software RAID with NTFS - Limitiations when using the MD driver - ChangeLog Overview ======== To mount an NTFS 1.2/3.x (Windows NT4/2000/XP) volume, use the filesystem type 'ntfs'. The driver currently works only in read-only mode, with no fault-tolerance or journalling supported. 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. 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= 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= 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= 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= 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. errors=opt What to do when critical file system 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 a 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 This 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. Features ======== - This is a complete rewrite of the NTFS driver that used to be in the kernel. This new driver implements NTFS read support and is functionally equivalent to the old ntfs driver. - 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. - 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. 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 Software RAID with NTFS ============================= For support of volume and stripe sets, use the kernel's Software RAID / MD driver and 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 "Limitiations 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 damange 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-disl 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.openprojects.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. Limitiations when using the 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! ChangeLog ========= Note, a technical ChangeLog aimed at kernel hackers is in fs/ntfs/ChangeLog. 2.1.2a: - Major bug fixes aleviating the hangs in statfs experienced by some users. 2.1.1a: - Major bug fix aleviating the random hangs experienced by some users. - Update handling of compressed files so people no longer get the frequently reported warning messages about initialized_size != data_size. 2.1.0a: - Sync up with ntfs 2.1.0. 2.1.0: - Add configuration option for developmental write support. - Initial implementation of file overwriting. (Writes to resident files are not written out to disk yet, so avoid writing to files smaller than about 1kiB.) - Intercept/abort changes in file size as they are not implemented yet. 2.0.25a: - Sync up with ntfs 2.0.25. 2.0.25: - Minor bugfixes in error code paths and small cleanups. 2.0.24: - Small internal cleanups. - Support for sendfile system call. (Christoph Hellwig) 2.0.23(a): - Massive internal locking changes to mft record locking. Fixes various race conditions and deadlocks. - Fix ntfs over loopback for compressed files by adding an optimization barrier. (gcc was screwing up otherwise ?) Thanks go to Christoph Hellwig for pointing these two out: - Remove now unused function fs/ntfs/malloc.h::vmalloc_nofs(). - Fix ntfs_free() for ia64 and parisc. 2.0.22a: - Sync with NTFS 2.0.22 and kernel 2.4.19. 2.0.22: - Small internal cleanups. 2.0.21a: - Resync 2.4.18 kernel backport with latest 2.5.x kernel ntfs release. 2.0.21: These only affect 32-bit architectures: - Check for, and refuse to mount too large volumes (maximum is 2TiB). - Check for, and refuse to open too large files and directories (maximum is 16TiB). 2.0.20: - Support non-resident directory index bitmaps. This means we now cope with huge directories without problems. - Fix a page leak that manifested itself in some cases when reading directory contents. - Internal cleanups. 2.0.19: - Fix race condition and improvements in block i/o interface. - Optimization when reading compressed files. 2.0.18: - Fix race condition in reading of compressed files. 2.0.17: - Cleanups and optimizations. 2.0.16: - Fix stupid bug introduced in 2.0.15 in new attribute inode API. - Big internal cleanup replacing the mftbmp access hacks by using the new attribute inode API instead. 2.0.15: - Bug fix in parsing of remount options. - Internal changes implementing attribute (fake) inodes allowing all attribute i/o to go via the page cache and to use all the normal vfs/mm functionality. 2.0.14: - Internal changes improving run list merging code and minor locking change to not rely on BKL in ntfs_statfs(). 2.0.13: - Internal changes towards using iget5_locked() in preparation for fake inodes and small cleanups to ntfs_volume structure. 2.0.12a: - Resync 2.4.18 backport with 2.0.12. 2.0.12: - Internal cleanups in address space operations made possible by the changes introduced in the previous release. 2.0.11: - Internal updates and cleanups introducing the first step towards fake inode based attribute i/o. 2.0.10: - Microsoft says that the maximum number of inodes is 2^32 - 1. Update the driver accordingly to only use 32-bits to store inode numbers on 32-bit architectures. This improves the speed of the driver a little. 2.0.9: - Change decompression engine to use a single buffer. This should not affect performance except perhaps on the most heavy i/o on SMP systems when accessing multiple compressed files from multiple devices simultaneously. - Minor updates and cleanups. 2.0.8: - Remove now obsolete show_inodes and posix mount option(s). - Restore show_sys_files mount option. - Add new mount option case_sensitive, to determine if the driver treats file names as case sensitive or not. - Mostly drop support for short file names (for backwards compatibility we only support accessing files via their short file name if one exists). - Fix dcache aliasing issues wrt short/long file names. - Cleanups and minor fixes. 2.0.7: - Just cleanups. 2.0.6b: - Remove relevant parts of the patch. 2.0.6a: - Backport from 2.5.x to 2.4.18. 2.0.6: - Major bugfix to make compatible with other kernel changes. This fixes the hangs/oopses on umount. - Locking cleanup in directory operations (remove BKL usage). 2.0.5: - Major buffer overflow bug fix. - Minor cleanups and updates for kernel 2.5.12. 2.0.4: - Cleanups and updates for kernel 2.5.11. 2.0.3: - Small bug fixes, cleanups, and performance improvements. 2.0.2: - Use default fmask of 0177 so that files are no executable by default. If you want owner executable files, just use fmask=0077. - Update for kernel 2.5.9 but preserve backwards compatibility with kernel 2.5.7. - Minor bug fixes, cleanups, and updates. 2.0.1: - Minor updates, primarily set the executable bit by default on files so they can be executed. 2.0.0: - Started ChangeLog.