Raspian, USB disk, change from GPT to MBR

[medwe]

I've been trying to do some things to change me exteral USB 1tb drive from GPT to MBR. I removed the partitions and then tried gdisk recovery option to change the disk to MBR, Now I have a disk that still appears to be GPT and it now also says I have a misaligned forced MBR. What I want to do, with no concern about any data (obviously since I removed the existing partitions), is some how just completely convert it from GPT to MBR. I want to use this on the Pi I am using as a server. I currently have 3 disks (USB, self powered, plugged into a powered hub) attached and mounted, but this GPT disk doesn't seem to be able to mount (I use mount via UUID in fstab). So, can anyone tell me how to do this from the command line if possible? I currently just use Putty to work on the server.

THANKS!

[elatllat]

use parted and mkfs

Code: Select all

parted -s /dev/sda mklabel mbr
parted -s /dev/sda mkpart primary 0% 100%
mkfs.ext4 -m 0 /dev/sda1

Edit; /gpt/mbr/

[rpdom]

use parted and mkfs

Code: Select all

parted -s /dev/sda mklabel gpt
parted -s /dev/sda mkpart primary 0% 100%
mkfs.ext4 -m 0 /dev/sda1

Wouldn't that create a GPT parition table on the drive, which is the opposite of what the OP requested?

Assuming there is no data that need to be retained I'd just trash the first few MB of the device, then create a new table with fdisk

Code: Select all

dd if=/dev/zero of=/dev/sda bs=1M count=1

[GTR2Fan]

Assuming that you have a Windows PC, the free version of MiniTool Partition Wizard can do this for you with just a few mouse clicks. It's a handy tool to have as it can handle Ext4 partitions too, so it provides a very easy point-and-click route to moving Pi OS /root partitions to hard drives if you ever fancy running your OS from a spinner...

http://www.partitionwizard.com/help/Con ... -disk.html

[medwe]

I tried the setting of the front-end of the disk to zeros - no errors where reported. I then went to fdisk via fdisk /dev/sdb. It claims the disk still has a GPT. I may try the Windows route - seems like it shouldn't be that hard to reinitialize a disk in Raspian.

Thanks for the replies!

[wdt]

A GPT disk has a backup partition table at the end of the disk,,
17 sectors perhaps
So use dd and skip (after a bit of calculation)

sorry, not skip,, seek (skip is for input files)