- Features
- Supported mount options
- Known bugs and (mis-)features
-- Using Software RAID with NTFS
-- Limitiations when using the MD driver
+- Using NTFS volume and stripe sets
+ - The Device-Mapper driver
+ - The Software RAID / MD driver
+ - Limitiations when using the MD driver
- ChangeLog
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
+use the kernel's Software RAID / MD driver. See section "Using Software RAID
with NTFS" for details.
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
+ (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
+- 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.
+ 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).
Supported mount options
list at sourceforge: linux-ntfs-dev@lists.sourceforge.net
-Using Software RAID with NTFS
-=============================
+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://linux-ntfs.sourceforge.net/downloads.html
+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):
+
+--- 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 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).
+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):
+
+--- 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):
+
+--- cut here ---
+# Ofs Size Raid Log Number Region Should Number Source Start Taget 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.
+
+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 entirey of the "Source Device"
+to the "Target Device" or if you specified multipled 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 "Limitiations when using
ntfs volume.
-Limitiations when using the MD driver
-=====================================
+Limitiations 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
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.
+
ChangeLog
=========
Note, a technical ChangeLog aimed at kernel hackers is in fs/ntfs/ChangeLog.
+2.1.22:
+ - Improve handling of ntfs volumes with errors.
+ - Fix various bugs and race conditions.
+2.1.21:
+ - Fix several race conditions and various other bugs.
+ - Many internal cleanups, code reorganization, optimizations, and mft
+ and index record writing code rewritten to fit in with the changes.
+ - Update Documentation/filesystems/ntfs.txt with instructions on how to
+ use the Device-Mapper driver with NTFS ftdisk/LDM raid.
+2.1.20:
+ - Fix two stupid bugs introduced in 2.1.18 release.
+2.1.19:
+ - Minor bugfix in handling of the default upcase table.
+ - Many internal cleanups and improvements. Many thanks to Linus
+ Torvalds and Al Viro for the help and advice with the sparse
+ annotations and cleanups.
+2.1.18:
+ - Fix scheduling latencies at mount time. (Ingo Molnar)
+ - Fix endianness bug in a little traversed portion of the attribute
+ lookup code.
+2.1.17:
+ - Fix bugs in mount time error code paths.
+2.1.16:
+ - Implement access time updates (including mtime and ctime).
+ - Implement fsync(2), fdatasync(2), and msync(2) system calls.
+ - Enable the readv(2) and writev(2) system calls.
+ - Enable access via the asynchronous io (aio) API by adding support for
+ the aio_read(3) and aio_write(3) functions.
+2.1.15:
+ - Invalidate quotas when (re)mounting read-write.
+ NOTE: This now only leave user space journalling on the side. (See
+ note for version 2.1.13, below.)
+2.1.14:
+ - Fix an NFSd caused deadlock reported by several users.
+2.1.13:
+ - Implement writing of inodes (access time updates are not implemented
+ yet so mounting with -o noatime,nodiratime is enforced).
+ - Enable writing out of resident files so you can now overwrite any
+ uncompressed, unencrypted, nonsparse file as long as you do not
+ change the file size.
+ - Add housekeeping of ntfs system files so that ntfsfix no longer needs
+ to be run after writing to an NTFS volume.
+ NOTE: This still leaves quota tracking and user space journalling on
+ the side but they should not cause data corruption. In the worst
+ case the charged quotas will be out of date ($Quota) and some
+ userspace applications might get confused due to the out of date
+ userspace journal ($UsnJrnl).
+2.1.12:
+ - Fix the second fix to the decompression engine from the 2.1.9 release
+ and some further internals cleanups.
+2.1.11:
+ - Driver internal cleanups.
+2.1.10:
+ - Force read-only (re)mounting of volumes with unsupported volume
+ flags and various cleanups.
+2.1.9:
+ - Fix two bugs in handling of corner cases in the decompression engine.
2.1.8:
- Read the $MFT mirror and compare it to the $MFT and if the two do not
match, force a read-only mount and do not allow read-write remounts.
git://git.onelab.eu / linux-2.6.git / blobdiff