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Autore: Fred
Data:  
To: dng
Oggetto: Re: [DNG] fdisk SD card partitioning question
On 6/12/22 14:09, Fred wrote:
> On 6/12/22 13:48, ael wrote:
>> On Sun, Jun 12, 2022 at 12:35:06PM -0700, Fred wrote:
>>> On 6/12/22 09:18, Antony Stone wrote:
>>>> On Sunday 12 June 2022 at 17:11:45, Fred wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> I have some directories I want to back up to an SD card while
>>>>> preserving
>>>>> the permissions.  I have tried to repartition a 64GB card and write an
>>>>> ext4 filesystem.
>>>>
>>>> What is the existing partition table?
>>>>
>>>> Out of interest, since this is ext4 and therefore Linux (not
>>>> Windows), why
>>>> partiton at all?  Why not just "mkfs.ext4 /dev/sdX"?
>>>>
>>>>> fdisk says the card has 124702720 sectors and has 59.5GB available.
>>>>> However it will not make a partition over 27.5GB.  Why and what to do?
>>
>> Are you sure that this is not just another example of "Flash Fraud"?
>> You could try running https://github.com/AltraMayor/f3 .
>>
>>
>>> Hi,
>>> As supplied the SD cards are intended to work with Windows.  Under Linux
>>> only root can write to them and the ownership can not be changed.  I
>>> want
>>> preserve permissions of data written to the card.
>>
>> I don't follow above. SD cards usually come with a vfat file system and
>> are indeed set up mainly for Windoze. But if you mount with
>> -o uid=someone,gid=someone,..
>> then that someone user can write.
>>
>> I do this all the time with a whole variety of sdhc cards. I only leave
>> them formated for vfat if I need to move them between other devices
>> (cameras, sat navs, ereaders which only read and write vfat). Otherwise
>> I use a better file system.
>>
>>>
>>> root@aragog:# /sbin/fdisk -l /dev/sdb
>>> Disk /dev/sdb: 27.48 GiB, 29504831488 bytes, 57626624 sectors
>>> Disk model: Card-Reader
>>> Units: sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>> Disklabel type: dos
>>> Disk identifier: 0x00000000
>>>
>>> Device     Boot Start       End   Sectors  Size Id Type
>>> /dev/sdb1       32768 124735487 124702720 59.5G  7 HPFS/NTFS/exFAT
>>>
>>> I don't know why the size is reported differently in two places.  It
>>> is a
>>> 64GB card.
>>
>> Are you sure?? Not a faked 32GB ?
>>
>>>
>>> I tried your dd command line and things have gone downhill as the
>>> 64GB card
>>> is now only 27.4GB.
>>
>> So almost certainly a fake. Did you but this from somewhere trustworthy?
>>
>>> root@aragog:# /sbin/fdisk -l /dev/sdb
>>> Disk /dev/sdb: 27.48 GiB, 29504831488 bytes, 57626624 sectors
>>> Disk model: Card-Reader
>>> Units: sectors of 1 * 512 = 512 bytes
>>> Sector size (logical/physical): 512 bytes / 512 bytes
>>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>>>
>>>
>>> I tried fdisk again with the same result.
>>>
>>> root@aragog:# /sbin/fdisk /dev/sdb
>>> Command (m for help): n
>>> Partition type
>>>     p   primary (0 primary, 0 extended, 4 free)
>>>     e   extended (container for logical partitions)
>>> Select (default p): p
>>> Partition number (1-4, default 1): 1
>>> First sector (2048-57626623, default 2048):
>>> Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-57626623, default
>>> 57626623):
>>>
>>> Created a new partition 1 of type 'Linux' and of size 27.5 GiB.
>>>
>>> Command (m for help): d
>>> Selected partition 1
>>> Partition 1 has been deleted.
>>>
>>> Command (m for help): n
>>> Partition type
>>>     p   primary (0 primary, 0 extended, 4 free)
>>>     e   extended (container for logical partitions)
>>> Select (default p): e
>>> Partition number (1-4, default 1): 1
>>> First sector (2048-57626623, default 2048):
>>> Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-57626623, default
>>> 57626623):
>>>
>>> Created a new partition 1 of type 'Extended' and of size 27.5 GiB.
>>>
>>>
>>> Any ideas?
>>
>> Yes. Almost  certainly a fake....
>>
>> ael
>>
> Hi,
> I recall a lot of discussion about this on either this list or the
> Debian list.  If the card was an offbrand I would assume it was fraud
> and would not have even asked here.  However, the card is a SanDisk. The
> packaging becomes destroyed in removing the card so I can't take it back
> to Walfart for exchange.
>
> I would like to try the f3 program.  How do I get the tarball from github?
>
> You said above that you use a better filesystem for the sdhc cards. Have
> you done that for a card over 32GB?  And how?
>
> Best regards,
> Fred
>
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Hi,

The f3probe utility says:

Good news: The device /dev/sdb is the real thing

And then it reports the same size as fdisk, 27.48GB usable even though
the card is plainly marked 64GB.

So, my question has been answered. Thanks for the help!

Best regards,
Fred