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Re: DD bs=4M option on USB mem-stick creates false format




Thomas Schmitt:
> Hi,
> 
> kAt wrote:
>>> /sbin/fdisk -l /dev/sdb
>> Disk /dev/sdb: 7.2 GiB, 7751073792 bytes, 15138816 sectors
> 
> Is this about the correct size of the stick ?

I suppose this is normal for an 8Gb usb stick. 249Mb go to firmware that
operates the stick????  I wouldn't know.

>> Units: sectors of 1 * 512 = 512 bytes
>> Sector size (logical/physical): 512 bytes / 512 bytes
>> I/O size (minimum/optimal): 512 bytes / 512 bytes
> 
> Looks like a normal block size for USB sticks and conventional disks.

So where does the false alert come from on Gparted about the 2048b?
Is it a problem with the way I restore the iso, a problem with the iso
that Rescatux forces (I wouldn't think so) or a problem with the stick
itself?

>> Device     Boot   Start     End Sectors  Size Id Type
>> /dev/sdb1  *         64 1374207 1374144  671M  0 Empty
>> /dev/sdb2       1297212 1298619    1408  704K ef EFI (FAT-12/16/32)
> 
> This is the MBR partition table. You may use fdisk to add a partition.
> (Let's hope it will not hate that sdb2 is located inside sdb1.)

why does this happen?  Again this is not an iso I created but downloaded
from Rescatux

>> echo 2 | sudo /sbin/gdisk -l /dev/sdb
>> Warning! Main partition table overlaps the first partition by 64 blocks!
>> You will need to delete this partition or resize it in another utility.
> 
> gdisk definitively hates the start of the outer partition.
> But starting at block 64 would mean that it would not be mountable.

So fdisk uses things differently than gdisk, or is the one using the other?

>> Number  Start (sector)    End (sector)  Size       Code  Name
>>   2         1297212         1298619   704.0 KiB   0700  ISOHybrid1
> 
> The EFI partition is more to its taste.

The EFI part is sdb2, right?  Which resides inside sdb1?

> As said, the GPT of an ISO with "mjg" layout is quite useless
> and i'd zeroize its header block at block address 1.

So it is normal that if you write such an iso in a 64Gb stick 63Gb
remain useless as long as this system is on it?  Strange but still
clueless of what all this means ...

> Have a nice day :)

You too

> Thomas

I am very far from undersdanding this but it is interesting to keep at it?

kAt