Re: [Linux-NTFS-Dev] ntfsresize shrinking

[Szakacsits Szabolcs]

Hi,

Thanks Nirranjan for the more details. As I thought it it's not an
ntfsresize issue itself but the process of resizing a partition,
partition manipulation. You're not the first one who had this problem
and also not the last one (partition manipulation isn't easy,
especially it's fairly messy). This is why ntfsresize and it's
documentation adds disk partitioning related warnings all over (during
execution, man page, FAQ).

On Tue, 21 Jan 2003, Nirranjan.K wrote:

> partitioning tool i used - parted 1.6.4
<
> [ ... shrink NTFS on an extended partition with ntfsresize ... ]
>
> Cluster size       : 4096
> Current volume size: 716543 clusters (2798 MB)
> New volume size    : 691200 clusters (2700 MB)
> [ ... ]
> ==> NTFS had been successfully resized on device /dev/hda6.
> ==> Now you can go on to resize/split the partition.

This is a very old development version of ntfsresize, what you
probably got from Bala. There were several changes since then before
releasing the beta a couple of days ago at

        http://sourceforge.net/project/showfiles.php?group_id=13956

Bigger changes include:

- sizes are printed in bytes not NTFS clusters. This gives immediate
  exact information where to resize the partition.

- resizing by cluster not supported anymore to prevent user
  confusions and trying to reduce user mistakes.

- k, M, G prefixes have changed from binary to decimal according to
  SI and other standards. Here is a summary how different tools use
  these units.
           http://physics.nist.gov/cuu/Units/prefixes.html
           http://physics.nist.gov/cuu/Units/binary.html
                               k        M          G
           old fdisk         2^10     2^20      10^3*2^20
           recent fdisk     10^3     10^6       10^9
           cfdisk           10^3     10^6       10^9
           ntfsresize       10^3     10^6       10^9
           sfdisk            2^10     2^20
           parted            2^10     2^20  (may change)
           fdisk (DOS)       2^10     2^20

- warnings about using a disk partitioner was added all over

- man page was added detailing disk partitining issues (well, not
  the case resizing a logical partition when there are other
  partition(s) behind it -- but it do work if disk partitioning
  done properly)

- ntfsresize FAQ was created with an example, among others,

        http://mlf.linux.rulez.org/mlf/ezaz/ntfsresize.html

- 'fdisk' is refered everywhere (man page, FAQ, when ntfsresize
  exits, etc) because that's what most available and tests were done.

> [ ... edit extended partition ... ]
>
> [ ... fdisk -lu output ... ]
>
> Partition table entries are not in disk order
>
> Now when i boot to windows. It asks for formating of
> NTFS partition (/dev/hda6),. i.e data lost

After the partition editing, the new partition table points to a
different place or overwrote the NTFS boot sector that's why Win can't
find it anymore.

You can ensure that ntfsresize doesn't damage your data if you reboot
to Windows right after running ntfsresize and *before* using a disk
partition tool. This way you can distinguish where the problem was
introduced.

If you have idea what the linux-ntfs team can do to prevent/reduce
these kind of disk partitioning mistakes please let us know, send
more documentation, etc.

Please also note from the ntfsresize FAQ this quote,

  "Question: Are there plans for cooperation with Parted?

   Yes. Parted is an open source partition manipulation program
   that also understands and can modify the filesystems on the
   partitions. Doing the support for Parted, before or after
   implementing full NTFS resize functionality (resizing fragmented
   volumes), depends on users' interest.

Hopefully when parted can use libntfs (work is still needed for
libntfs) then this kind of mistakes will be significantly reduced
or gone.

Thank you for your feedbacks again.

        Szaka