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ntfsprogs for Virtual Disk Partitions

November 29th, 2009

The ntfsprogs package provides a nice set of tools for performing operations on NTFS file systems from non-Windows environments.  There are many uses for these, and I’ve found them helpful in virtualized environments when dealing with virtual disk images.  In particular, they allow for the easy restoration of individual files from NTFS virtual disks from the host OS.  These tools however, are only capable of operating on entire devices, and in many cases the individual partitions of virtual disk images are not exposed as block devices by the operating system, preventing these tools from working.

As a workaround for this, I’ve created a patch against ntfsprogs 2.0.0 that adds an --offset option to most of the tools, allowing a partition offset, in bytes from the start of the device, to be specified.

These patches were tested on OpenSolaris, but should work with other systems as well.  They include a Solaris patch to fix compilation issues on Solaris.  They are available in the following forms:

Compiling the tools can be done with:

$ wget http://www.edplese.com/files/ntfsprogs-2.0.0-offset.tar.gz
$ gzcat ntfsprogs-2.0.0-offset.tar.gz | tar -xf -
$ cd ntfsprogs-2.0.0-offset
$ ./configure && make

Once compiled, the tools can be installed with make install, or run in place from the ntfsprogs-2.0.0-offset/ntfsprogs directory without having to install them.

The following example demonstrates the tools operating on a snapshot of an NTFS volume stored on a ZFS zvol block device.

# lspart.py /dev/zvol/dsk/rpool/xvm/win2k8@installed
  Start Offset    Size  Type
       1048576  100.0M  07 Windows NTFS
     105906176   15.9G  07 Windows NTFS
             0    0.0B  00 Empty
             0    0.0B  00 Empty
# ntfsls /dev/zvol/dsk/rpool/xvm/win2k8@installed
Failed to startup volume: Invalid argument.
Failed to mount '/dev/zvol/dsk/rpool/xvm/win2k8': Invalid argument.
The device '/dev/zvol/dsk/rpool/xvm/win2k8' doesn't have a valid NTFS.
Maybe you selected the wrong device? Or the whole disk instead of a
partition (e.g. /dev/hda, not /dev/hda1)? Or the other way around?
# ntfsls --offset 1048576 /dev/zvol/dsk/rpool/xvm/win2k8@installed
System Volume Information
# ntfsls --offset 105906176 /dev/zvol/dsk/rpool/xvm/win2k8@installed
Documents and Settings
Program Files
Program Files (x86)
System Volume Information
# ntfscat --offset 105906176 /dev/zvol/dsk/rpool/xvm/win2k8@installed \
          Windows/System32/notepad.exe > notepad.exe
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