Jean-Pierre André wrote:
> Martin Mokrejs wrote:
>> Hi Jean-Pierre,
>>
>>    thank you for your quick answer. Comments below.
>>
>> Jean-Pierre André wrote:
>>> Hi,
>>>
>>> Martin Mokrejs wrote:
>>>
>>>  > Hi,
>>>  >    I am configuring a Linux under VirtualBox-5.0.0-rc3 and one of the
>>>  > partition will be NTFS. The disk is raw disk, on host exposed as
>>>  > /dev/sdc, on guest appears as /dev/sda.
>>>  >
>>>  > It seems detection of virtual drive geometry fails or mkntfs is
>>> broken.
>>>  > Seems I can provide mkntfs with cyl/head/sect counts but what is the
>>>  > cause?
>>>  >
>>>  > It seems very dangerous to blindly set starting sector to zero and
>>>  > starting zero-ing my drive.
>>>
>>> The starting sector of an NTFS partition is only used for booting
>>> Windows, and it is a 32-bit field which cannot hold 5860533134.
>
> Please read 4357349376 (initial sector of sdc5)
>
>>> There is no problem with a null starting sector if this not a
>>> Windows system partition.
>>
>> Well, in my case my aim was to use it only for data, so fine with me, but,
>> would you please make the message from mkntfs clearer? Also, could it
>> include
>> the actually obtained value, so 5860533134 in my case? And explain the
>> 32-bit issue?
>>
>>
>>> Likewise you cannot encode 5860533134 into C/H/S values (even
>>> manually !), and they are only used for booting Windows.
>>>
>>> Both are values to be stored in the boot sector of the NTFS
>>> partition (not the boot sector of the drive).
>
> [...]
>
>>> This is unusual, so far all the 3TB drives I have heard of
>>> have 4K sectors. As a consequence in your case the number
>>> of sectors does not fit into a 32-bit word.
>>
>> Hmm, this is Lacie D2 QUADRA 3TB drive, pretty expensive one with eSATA,
>> FireWire, USB3.0. So I should look for a firmware flash? ;-)
>
> This can also result from the hardware emulating a 4K-byte
> sector on 512-byte sectors... or VirtualBox doing the
> emulation. In both cases writing a 512-byte sector implies
> reading a 4K sector, updating 512 bytes and writing the 4K
> sector, which is inefficient.
>
> You should ask the vendor.

Will do. For your info: https://www.lacie.com/products/product.htm?id=10554


>>> You should have dumped the beginning of /dev/sdc5 to locate
>>> an NTFS partition with the fields related to the geometry of
>>> the drive left unfilled.
>
> [...]
>
>> Aha. How? Via dd with offset=4357349376-1 ?
>
> Either :
>
> dd if=/dev/sdc5 bs=512 count=1 | od -t x1
>
> or (provided 4357349376 does not get truncated) :
>
> dd if=/dev/sdc skip=4357349376 bs=512 count=1 | od -t x1
>
> or :
>
> dd if=/dev/sdc skip=544668672 bs=4096 count=1 | od -t x1 | head -n 32

I did this form the hosting Linux-3.10.78 kernel (as was the smartctl and other 
commands
in my previous emails, just to avoid potential issues with VirtualBox):

vostro ~ # dd if=/dev/sdc5 bs=512 count=1 | od -t x1
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.00219365 s, 233 kB/s
0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0001000
vostro ~ # dd if=/dev/sdc skip=4357349376 bs=512 count=1 | od -t x1
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.00157466 s, 325 kB/s
0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0001000
vostro ~ # dd if=/dev/sdc skip=544668672 bs=4096 count=1 | od -t x1 | head -n 32
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 0.00156452 s, 2.6 MB/s
0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0010000
vostro ~ #

>
>
>>
>>>
>>> Main question : did you format /dev/sdc5 and is it usable ?
>>
>> I did not let it continue, I was so scared to zap my raw drive ... ;-)
>> I will first resolve with you what is in the NTFS boot block .;-)
>
> Oh, and if you do not use option -f it will take hours
> with no value added.


Thank you for reminding me, will get to it after next email round.;-)
Martin

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