HOWTO: fix HDD partition order with fdisk in Linux

Sometimes (usually after some repartitioning operations) disk partitions can get into the wrong order (e. g., "sdb1 sdb7 sdb2 sdb5 sdb4 sdb3", as you can see it in lsblk / fdisk / Parted / GParted etc.).

Usually it's harmless, but anyway can be easily fixed in Linux with a fdisk utility (from the util-linux package): just start fdisk with a HDD device as an argument (e. g.: fdisk /dev/sdb), then sequentially press 'x', 'f' and 'w' keys, and finally reboot your system (for the changes to take effect).

Be careful:

1. you can do this from a some sort of Live CD / Live USB environment;
   please don't try this on a running production system;
2. partition numbers get changed, and some OS's (and especially OS bootloaders) sometimes don't like this;
3. the partition table can get corrupted — make backups prior to any experiments.

Here is a sample output log:

# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.21.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): x

Expert command (m for help): m
Command action
   b   move beginning of data in a partition
   c   change number of cylinders
   d   print the raw data in the partition table
   e   list extended partitions
   f   fix partition order
   g   create an IRIX (SGI) partition table
   h   change number of heads
   i   change the disk identifier
   m   print this menu
   p   print the partition table
   q   quit without saving changes
   r   return to main menu
   s   change number of sectors/track
   v   verify the partition table
   w   write table to disk and exit

Expert command (m for help): f
Done.

Expert command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

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Last updated: 2014-06-17