Disque externe illisible

L'ancien disque était en NTFS.

Car je ne connaissais pas jusque là l'exFAT ; je ne pouvais écrire sur le disque qu'en utilisant Paragon NTFS ; c'est le format d'origine du disque à l'achat.
 
Ah d'accord.

- bon : je crois qu'on sait tout ce qu'il y a à chercher sur l'ancien disque à présent.​
 
Bloc de code:
Last login: Wed Apr 29 09:45:30 on console
macbook-air-de-thomas:~ Thomas$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk1         121.1 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +121.1 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            96.2 GB    disk1s1
   2:                APFS Volume Preboot                 20.4 MB    disk1s2
   3:                APFS Volume Recovery                519.1 MB   disk1s3
   4:                APFS Volume VM                      2.1 GB     disk1s4

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *3.0 TB     disk2

macbook-air-de-thomas:~ Thomas$
 
Les 3 To sont bien reconnus mais il n'y a aucune table de partition.

- passe la commande :​
Bloc de code:
sudo fdisk /dev/disk2

  • et poste le retour => qu'on voie ce que ça donne.
 
Bloc de code:
macbook-air-de-thomas:~ Thomas$ sudo fdisk /dev/disk2
Password:
Disk: /dev/disk2    geometry: 45599/255/63 [732558336 sectors]
Sector size: 4096 bytes
Signature: 0x89AD
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: 0C  947 174  42 -  971  56   6 [3041797072 -   62991746] Win95 FAT32L
 2: 32  114  18  25 -  984 182  46 [2128399486 - 1804427980] <Unknown ID>
 3: 32  114 195  25 -  984 182  46 [2128399486 - 1804427980] <Unknown ID>
 4: B7  359 195  35 -  736 215  24 [3056506349 - 1111835718] BSDI filesy*
macbook-air-de-thomas:~ Thomas$
 
On apprend que la taille du bloc (sector) = 4096 octets.

- alors pourquoi ne pas voir quel est le contenu du bloc n°256 ? - pour ne pas avoir un affichage prolixe > on va explorer les 512 premiers octets de ce bloc. Passe la commande :​
Bloc de code:
sudo dd if=/dev/disk2 bs=512 count=1 skip=2048 | hexdump -Cv

  • poste l'affichage retourné.
 
Aïe ! C'est vide ...

Bloc de code:
macbook-air-de-thomas:~ Thomas$ sudo dd if=/dev/disk2 bs=512 count=1 skip=2048 | hexdump -Cv
Password:
1+0 records in
1+0 records out
512 bytes transferred in 0.000629 secs (814057 bytes/sec)
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000120  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000140  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000150  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000170  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000200
macbook-air-de-thomas:~ Thomas$
 
Le 1er bloc ou super-bloc du NTFS contient le descriptif du volume. D'après le modèle de ton disque neuf > ce bloc doit commencer par ceci -->
Bloc de code:
00000000  eb 52 90 4e 54 46 53 20  20 20 20 00 10 01 00 00  |.R.NTFS    .....|

  • avec donc la mention NTFS dans la colonne de translation de hexdump. Tant qu'on ne tiendra pas un bloc commençant par cette inscription > rien ne sera fait.

Ma commande pourrait être étendue de la manière suivante : prendre le gabarit de bloc 4096 octets > échapper seulement le 1er bloc (= bloc n°0 porteur par définition de la table MBR) > et prendre comme comptage de blocs à cloner par dd / afficher dans hexdump une valeur de 100. Tu passes la commande pour toi => ce qui te donne un affichage super-prolixe dans le terminal > puis tu balaies de haut en bas en accéléré cet affichage pour voir si tu tombes sur des inscriptions. Si tu n'as rien > tu repasses une commande échappant cette fois les 100 premiers blocs et clonant / affichant les 100 suivants.

- qu'est-ce que tu en penses ?​
 
Oui je comprends tout à fait : je vais balayer jusqu'à trouver ce motif en utilisant ta commande.

Ne serait-ce pas possible que nous ayons supprimé ce bloc lors de nos précédentes manipulations sur ce disque ?
 
Il est très possible qu'un effacement soit intervenu - effectivement.

- donc tu peux passer la commande :​
Bloc de code:
sudo dd if=/dev/disk2 bs=4096 count=100 skip=1 | hexdump -Cv

  • qui clone / affiche les blocs de 1 à 100. Tu vas avoir droit à un affichage étendu. Tu le parcours en vitesse pour voir s'il y a des inscriptions à un moment donné.
 
Je retrouve ce motif à 2 reprises :

Bloc de code:
00004c00  eb 58 90 42 53 44 20 20  34 2e 34 00 02 01 20 00  |.X.BSD  4.4... .|
00004c10  02 00 00 00 00 f0 00 00  20 00 10 00 00 00 00 00  |........ .......|
00004c20  00 40 06 00 4f 0c 00 00  00 00 00 00 02 00 00 00  |[email protected]...........|
00004c30  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00004c40  00 00 29 ed 17 e3 67 45  46 49 20 20 20 20 20 20  |..)...gEFI      |
00004c50  20 20 46 41 54 33 32 20  20 20 fa 31 c0 8e d0 bc  |  FAT32   .1....|
00004c60  00 7c fb 8e d8 e8 00 00  5e 83 c6 19 bb 07 00 fc  |.|......^.......|
00004c70  ac 84 c0 74 06 b4 0e cd  10 eb f5 30 e4 cd 16 cd  |...t.......0....|
00004c80  19 0d 0a 4e 6f 6e 2d 73  79 73 74 65 6d 20 64 69  |...Non-system di|
00004c90  73 6b 0d 0a 50 72 65 73  73 20 61 6e 79 20 6b 65  |sk..Press any ke|
00004ca0  79 20 74 6f 20 72 65 62  6f 6f 74 0d 0a 00 00 00  |y to reboot.....|

Et ceci un peu plus loin mais pas d'intérêt :

Bloc de code:
100+0 records in
100+0 records out
00051110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00051120  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00051130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
409600 bytes transferred in 10.215522 secs (40096 bytes/sec)
 
Alors c'est le super-bloc du NTFS qui serait toujours inscrit sur les blocs !

- dans l'ensemble de l'affichage que tu as eu --> où se situe environ cet affichage : 1er tiers ? - milieu ?​
 
Je retrouve ces inscriptions à 2 reprises, légèrement espacées, entre 5 à 10% de l'affichage total.

Tu me parles de super-bloc NTFS mais je vois pourtant écrit FAT32 ...

Sûrement inutile, mais j'ai aussi trouvé ça dans le premier quart de l'affichage :
Bloc de code:
00008000  f0 ff ff 0f ff ff ff ff  ff ff ff 0f 00 00 00 00  |................|
 
Ah ! oui : tu as raison. Il s'agit bien de FAT-32. Ce qui correspondrait à une ancienne partition EFI dont le système de fichiers est toujours en FAT-32. On laisse tomber cette piste.

- pas d'autre inscription ailleurs dans l'affichage ?​
 
Non, pas d’autres traces sur ces 100 premiers blocs.
Si on se base sur le disque étudié hier, le bloc qui nous intéresse n’est-il pas le 256 ?
 
Si tu prends ma commande :
Bloc de code:
sudo dd if=/dev/disk2 bs=4096 count=100 skip=1 | hexdump -Cv

  • tu peux considérer que la seule variable ici est l'argument skip=1. Qui signifie échapper le 1er bloc (= bloc n°0) > ce qui fait qu'avec l'argument : count=100 les blocs n°1 à 100 vont être clonés / affichés. Donc en 2è commande > tu passes la même mais avec skip=101 (pour échapper les 101 premiers blocs (incluant le bloc n°0) et scanner les 100 blocs d'après). Puis skip=201 > skip=301...

Je te conseille de fermer la 1ère fenêtre de terminal et d'en ouvrir une nouvelle chaque fois (via ⌘N) afin de purger l'affichage antérieur. Tu te focalises sur la colonne de droite des inscriptions lisibles et tu cherches à repérer ceci -->
Bloc de code:
  |.R.NTFS    .....|
  |........?.......|
  |...........+....|
  |................|
  |.........K......|
  |.....3.....|.h..|
  |..hf......f.>..N|
  |TFSu..A..U..r...|
  |U.u.....u.......|
  |.h...H..........|
  |.....X.r.;...u..|
  |........Z3... +.|
  |f...............|
  |K.+.w......f#.u-|
  |f..TCPAu$....r..|
  |h...hR..h..fSfSf|
  |U...h..fa....3..|
  |.............f`.|
  |.f...f.....fh...|
  |.fP.Sh..h...B...|
  |.......fY[ZfYfY.|
  |....f...........|
  |...u...fa.......|
  |............<.t.|
  |............Erre|
  |ur lecture disqu|
  |e...BOOTMGR comp|
  |ress....Ctrl+Alt|
  |+Suppr pour red.|
  |marrer...start..|
 
Bonjour @macomaniac

J'ai utilisé ta commande en faisant varier le paramètre skip jusqu'à 701 pour enfin voir quelque chose :

Bloc de code:
0005fc00  45 46 49 20 20 20 20 20  20 20 20 28 00 00 00 00  |EFI        (....|
0005fc10  00 00 00 00 00 00 28 82  02 41 00 00 00 00 00 00  |......(..A......|
0005fc20  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc30  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc50  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc60  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc70  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc80  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fc90  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fca0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fcb0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fcc0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fcd0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fce0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fcf0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd10  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd20  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd30  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd50  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd60  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd70  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd80  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fd90  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fda0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fdb0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fdc0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fdd0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fde0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fdf0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe10  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe20  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe30  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe50  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe60  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe70  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe80  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fe90  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fea0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005feb0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fec0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fed0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fee0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fef0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff10  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff20  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff30  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff50  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff60  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff70  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff80  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ff90  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ffa0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ffb0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ffc0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ffd0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005ffe0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
0005fff0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00060000  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|
00060010  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|
00060020  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|
00060030  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|
00060040  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|
00060050  19 72 32 b6 ee d8 7e cc  dc 7e cc 62 8d 6b be c3  |.r2...~..~.b.k..|

Le motif situé en bas de ce bloc de code se retrouve ensuite au minimum jusqu'à skip=4001 en continu.

Le bloc 256 (2048 en réalité car multiplié par 8), sur lequel nous avions pu lire NTFS sur le nouveau disque, est vide sur mon disque :

Bloc de code:
macbook-air-de-thomas:~ Thomas$ sudo dd if=/dev/disk2 bs=512 count=1 skip=2048 | hexdump -Cv
Password:
1+0 records in
1+0 records out
512 bytes transferred in 0.000327 secs (1565221 bytes/sec)
00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000120  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000140  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000150  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000170  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000200
macbook-air-de-thomas:~ Thomas$

Partant du principe que je n'ai pas repartitionné mon disque par le passé et qu'il était dans sa configuration d'origine jusqu'à ce que nous cherchions à recréer des tables MBR ou GPT (alors que le boîtier acheté en remplacement et son défaut d'émulation était la seule cause au problème!), ne pourrions-nous pas recréer une MBR avec une seule partition NTFS commençant au bloc 256 ? Ce qui afficherait un volume dans lequel, espérons-le, se trouveraient mes données ?
 
On a exploré le bloc n° 256 (en computation de blocs de 4096 octets) : il est vide.

- si donc on recrée un descripteur MBR de partition dont le bloc de tête soit le n°256 => aucun super-bloc de système de fichiers ntfs ne sera récupéré par là en bloc de départ => et donc aucun volume ne montera affichant des fichiers. On n'aura créé sur le disque > par projection logique du descripteur MBR => qu'un conteneur de blocs bruts de type : Windows_NTFS ou Microsoft Basic Data.