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Mick 02-20-2010 10:23 AM

Resizing ntfs creates a hidden partition
 
Hi All,

I am resizing a Windows partition to get some space for Gentoo. I
noticed that when gparted finished and I rebooted the machine there is
a blank unallocated space in front of the Windows 7 partition, shown
below as 6.33MB:

================================================== =
cfdisk (util-linux-ng 2.16.1)

Disk Drive: /dev/sda
Size: 500107862016 bytes, 500.1 GB
Heads: 255 Sectors per Track: 63 Cylinders: 60801

Name Flags Part Type FS Type [Label] Size (MB)
------------------------------------------------------------------------------
sda1 Primary Dell Utility 41.13
sda2 Boot Primary NTFS [] 15728.64*
Pri/Log Free Space 6.33*
sda3 Primary NTFS [] 52426.47*
Pri/Log Free Space 431902.70*

================================================== =

Also, when I used gparted to create a new extended partition over the
431G free space at the end of the disk I ended up with a similar small
unallocated space in front of it. This is something I have observed
happening recently on 3 laptops that I have worked on, i.e. resizing
or creating a new partition inevitably creates a small blank partition
in front of it.

Looking at the sectors table I see this:
================================================== =
Partition Table for /dev/sda

First Last
# Type Sector Sector Offset Length Filesystem Type (ID) Flag
-- ------- ----------- ----------- ------ ----------- -------------------- ----
1 Primary 0 80324 63 80325 Dell Utility (DE) None
2 Primary 80325 30800324* 0 30720000*HPFS/NTFS (07) Boot
Pri/Log 30800325* 30812669 0 12345*Free Space None
3 Primary 30812670 133208104* 0 102395435*HPFS/NTFS (07) None
Pri/Log 133208105* 976768064 0 843559960*Free Space None
================================================== =

I am not sure what the asterisks are for after the last sector on the
second and third partitions.

Could this empty space jump be related to gparted somehow shifting the
start of a partition to make it align with a particular sector as per
previous thread on the 4k sector topic?

Should I do anything about it, or just run with it and let gparted
align what it wants to align as part of the partitioning process?
--
Regards,
Mick

Stroller 02-20-2010 12:54 PM

Resizing ntfs creates a hidden partition
 
On 20 Feb 2010, at 11:23, Mick wrote:

...
================================================== =
cfdisk (util-linux-ng 2.16.1)
...
Pri/Log 133208105* 976768064 0 843559960*Free
Space None

================================================== =

I am not sure what the asterisks are for after the last sector on the
second and third partitions.


I read the manpage for you:

... It can also display the size in sec-
tors and cylinders (see the change units command below). If
an aster-
isk (*) appears after the size, this means that the
partition is not

aligned on cylinder boundaries.

On most pagers you can search for "asterisk" by pressing the forward-
slash ("/") key and typing "asterisk".


Stroller.

Stefan Schulte 02-20-2010 12:59 PM

Resizing ntfs creates a hidden partition
 
Hi Mick,

AFAIK the asterisk behind the partition just indicates, that it is not
aligned to a cylinder boundary. I think this doesnt have any effect (or
maybe some old OS like DOS depend on it). If you use cfdisk for
partitioning you can avoid that by given the space in c(ylinders). e.g.
New Partition with a size of '100c'.

I guess your hidden partition has something to do with Windows
behaviour, because if you install Windows and create partitions during
the installation process, it also creates an extra 8MB partition.
Maybe gparted adopted that behaviour.

But I can't tell you the reason why. Some people say it's for temp data
(which I doubt) and others say it's used to store metadatas if the user
decides to use flexible disks or software RAIDs.

I just can say that windows is running fine without it on my computer,
because i decided to partition with cfdisk before running the
installation.

On Sat, Feb 20, 2010 at 11:23:27AM +0000, Mick wrote:
> Hi All,
>
> I am resizing a Windows partition to get some space for Gentoo. I
> noticed that when gparted finished and I rebooted the machine there is
> a blank unallocated space in front of the Windows 7 partition, shown
> below as 6.33MB:
>
> ================================================== =
> cfdisk (util-linux-ng 2.16.1)
>
> Disk Drive: /dev/sda
> Size: 500107862016 bytes, 500.1 GB
> Heads: 255 Sectors per Track: 63 Cylinders: 60801
>
> Name Flags Part Type FS Type [Label] Size (MB)
> ------------------------------------------------------------------------------
> sda1 Primary Dell Utility 41.13
> sda2 Boot Primary NTFS [] 15728.64*
> Pri/Log Free Space 6.33*
> sda3 Primary NTFS [] 52426.47*
> Pri/Log Free Space 431902.70*
>
> ================================================== =
>
> Also, when I used gparted to create a new extended partition over the
> 431G free space at the end of the disk I ended up with a similar small
> unallocated space in front of it. This is something I have observed
> happening recently on 3 laptops that I have worked on, i.e. resizing
> or creating a new partition inevitably creates a small blank partition
> in front of it.
>
> Looking at the sectors table I see this:
> ================================================== =
> Partition Table for /dev/sda
>
> First Last
> # Type Sector Sector Offset Length Filesystem Type (ID) Flag
> -- ------- ----------- ----------- ------ ----------- -------------------- ----
> 1 Primary 0 80324 63 80325 Dell Utility (DE) None
> 2 Primary 80325 30800324* 0 30720000*HPFS/NTFS (07) Boot
> Pri/Log 30800325* 30812669 0 12345*Free Space None
> 3 Primary 30812670 133208104* 0 102395435*HPFS/NTFS (07) None
> Pri/Log 133208105* 976768064 0 843559960*Free Space None
> ================================================== =
>
> I am not sure what the asterisks are for after the last sector on the
> second and third partitions.
>
> Could this empty space jump be related to gparted somehow shifting the
> start of a partition to make it align with a particular sector as per
> previous thread on the 4k sector topic?
>
> Should I do anything about it, or just run with it and let gparted
> align what it wants to align as part of the partitioning process?
> --
> Regards,
> Mick
>

Mick 02-21-2010 01:47 PM

Resizing ntfs creates a hidden partition
 
On Saturday 20 February 2010 13:59:38 Stefan Schulte wrote:
> Hi Mick,
>
> AFAIK the asterisk behind the partition just indicates, that it is not
> aligned to a cylinder boundary. I think this doesnt have any effect (or
> maybe some old OS like DOS depend on it). If you use cfdisk for
> partitioning you can avoid that by given the space in c(ylinders). e.g.
> New Partition with a size of '100c'.
>
> I guess your hidden partition has something to do with Windows
> behaviour, because if you install Windows and create partitions during
> the installation process, it also creates an extra 8MB partition.
> Maybe gparted adopted that behaviour.
>
> But I can't tell you the reason why. Some people say it's for temp data
> (which I doubt) and others say it's used to store metadatas if the user
> decides to use flexible disks or software RAIDs.
>
> I just can say that windows is running fine without it on my computer,
> because i decided to partition with cfdisk before running the
> installation.

Thank you both for your responses. I failed to notice that gparted now has a
handy 'align on cylinder' tick box. That's what I think shifts partitions
along until there is alignment with the cylinder boundary.
--
Regards,
Mick


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