復原GPT硬碟分割區

我的一顆 WD 2TB 綠標的分割區毀損了，使用 Gparted/Testdisk 都找不到可用的復原工具，
後來使用 Gdisk 就簡單的修復了。

#gdisk /dev/sdb
GPT fdisk (gdisk) version 0.8.5

Caution: invalid main GPT header, but valid backup; regenerating main header
from backup!

Caution! After loading partitions, the CRC doesn't check out!
Warning! Main partition table CRC mismatch! Loaded backup partition table
instead of main partition table!

Warning! One or more CRCs don't match. You should repair the disk!

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: damaged

****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************

Command (? for help): ?
b    back up GPT data to a file
c    change a partition's name
d    delete a partition
i    show detailed information on a partition
l    list known partition types
n    add a new partition
o    create a new empty GUID partition table (GPT)
p    print the partition table
q    quit without saving changes
r    recovery and transformation options (experts only)
s    sort partitions
t    change a partition's type code
v    verify disk
w    write table to disk and exit
x    extra functionality (experts only)
?    print this menu

Command (? for help): x

可以看到 GPT 已毀損了，進入 extra functionality (experts only) 模式，出現：

Expert command (? for help): ?
a    set attributes
c    change partition GUID
d    display the sector alignment value
e    relocate backup data structures to the end of the disk
g    change disk GUID
h    recompute CHS values in protective/hybrid MBR
i    show detailed information on a partition
l    set the sector alignment value
m    return to main menu
n    create a new protective MBR
o    print protective MBR data
p    print the partition table
q    quit without saving changes
r    recovery and transformation options (experts only)
s    resize partition table
t    transpose two partition table entries
u    Replicate partition table on new device
v    verify disk
w    write table to disk and exit
z    zap (destroy) GPT data structures and exit
?    print this menu

Expert command (? for help): r

再進入 recovery and transformation options (experts only)：

 Recovery/transformation command (? for help): ?
b    use backup GPT header (rebuilding main)
c    load backup partition table from disk (rebuilding main)
d    use main GPT header (rebuilding backup)
e    load main partition table from disk (rebuilding backup)
f    load MBR and build fresh GPT from it
g    convert GPT into MBR and exit
h    make hybrid MBR
i    show detailed information on a partition
l    load partition data from a backup file
m    return to main menu
o    print protective MBR data
p    print the partition table
q    quit without saving changes
t    transform BSD disklabel partition
v    verify disk
w    write table to disk and exit
x    extra functionality (experts only)
?    print this menu

Recovery/transformation command (? for help): b

 然後使用 use backup GPT header (rebuilding main)，此時並不會出現任何訊息，最後 w 寫入硬碟即大功告成！

Recovery/transformation command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/sdb.
The operation has completed successfully.