Some linux distributions impose to use GPT (GUID Partition Table) insted of traditional MBR. If you have an already installed linux system using MBR partition table and you want to convert it to a freshly new GPT table without data loss, here is the solution.

All you need is a GParted Live CD. You need to boot with the GParted Live CD and once the system started, in terminal you have to type the following commands (let’s assume /dev/sda hard disk):

sudo gdisk /dev/sda

then type the w command to convert MBR to GPT partition table. You will get a message:

Find checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!
Do you want to proceed (Y/N): Y

You type Y and if everything is ok with this convertion, you’ll get another message:

OK; writing new GUID partition table (GPT) to /dev/sda. The operation completed successfully.

That’s it! You can now boot with you new Linux distribution suppurtiong only GPT partition tables.