IMPORTANT: Per accedir als fitxer de subversion: http://acacha.org/svn (sense password). Poc a poc s'aniran migrant els enllaços. Encara però funciona el subversion de la farga però no se sap fins quan... (usuari: prova i la paraula de pas 123456)

IMPORTANT: Les noves versions d'Ubuntu (TODO: A partir de quan?) utilitzant el sistema de particions GPT. Tingueu en compte a l'hora de recuperar dades d'aquests discos ja que utilitzant eines tradicionals com fdisk les particions no es detectaran i us pot semblar que teniu un disc buit sense particions!

TODO

In computer hardware, GUID Partition Table (GPT) is a standard for the layout of the partition table on a physical hard disk. It forms a part of the Extensible Firmware Interface (EFI) standard, which is Intel's proposed replacement for the PC BIOS. It is also used on some BIOS systems because of the limitations of MBR partition tables. GPT allows for a maximum disk and partition size of 9.4 zettabytes (9.4 × 1021 bytes[1]). As of 2010, most current operating systems support GPT, although some operating systems (including Mac OS X and Windows) require systems with EFI hardware to support booting from GPT partitions.

The MBR partition table restricts partition sizes to a maximum of 2.19 terabytes (2.19 × 1012 bytes) or almost exactly 2 TiB (2,199,023,255,552 bytes or 4,294,967,296 (232−1) sectors × 512 (29) bytes per sector).[2] GPT supports partition sizes up to 9.4 zettabytes or 8 ZiB−512 bytes (9,444,732,965,739,290,426,880 bytes or 18,446,744,073,709,551,615 (264−1) sectors × 512 (29) bytes per sector). Diagram illustrating the layout of the GUID Partition Table scheme. In this example, each logical block (LBA) is 512 bytes in size, and each partition entry is 128 bytes. LBA addresses that are negative indicate position from the end of the volume, with −1 as the last addressable block.

The widespread MBR partitioning scheme, dating from the early 1980s, imposed limitations which affected the use of modern hardware. Intel therefore developed a new partition-table format in the late 1990s as part of what eventually became UEFI. The GPT as of 2010 forms a subset of the UEFI specification.[3]

Com funciona ?

Que mostra fdisk:

$ sudo fdisk -l
...
Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xcdf8556a

Dispositiu Arrenc.   Inici         Final    Blocs    Id  Sistema
/dev/sdb1   *          63   976768064   488384001   83  Linux

WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util fdisk doesn't support GPT. Use GNU Parted.

Com podeu veure cal utilitzar l'eina parted.

Troubleshooting. Resol·lució de problemes

No funciona fdisk amb les particions GPT

Utilitzeu parted:

$ sudo parted -l
Model: ATA OCZ-AGILITY3 (scsi)
Disk /dev/sda: 120GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End    Size    Type      File system     Flags
 1      1049kB  103GB  103GB   primary   ext4            boot
 2      103GB   120GB  17,1GB  extended
 5      103GB   120GB  17,1GB  logical   linux-swap(v1) 


Model: ATA ST3500820AS (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End    Size   Type     File system  Flags
 1      32,3kB  500GB  500GB  primary  ext3         boot


Model: ATA Hitachi HDS72101 (scsi)
Disk /dev/sdc: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt 

Number  Start   End     Size    File system     Name  Flags
 1      17,4kB  20,0MB  20,0MB  fat16                 bios_grub
 2      20,0MB  996GB   996GB   ext4
 3      996GB   1000GB  4178MB  linux-swap(v1)

Recuperar una partició GPT que s'ha posat per error com a DOS

Suposem que és el tercer disc (/dev/sdc):

$ sudo parted /dev/sdc
(parted) set
Warning: /dev/sda contains GPT signatures, indicating that it has a GPT table.  However, it does not have a valid fake msdos partition table, as
it should.  Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables.  Or perhaps you deleted the GPT
table, and are now using an msdos partition table.  Is this a GPT partition table?
Yes/No? yes
Partition number? 1
Flag to Invert? bios_grub
New state?  on/[off]? on

I ja teniu la partició recuperada.

Vegeu també

Enllaços externs