Boot partition on GPT USB. Other Partitions on MBR Hard Disk.Possible?

Question

Hi all,
I have successfully installed Arch on my 8GB USB with a GPT. I didn t want to harm my HD with Windows initially. My HD is MBR.
I was wondering if it was possible to move the Home and Root partitions into the HD on specifically ext4 partitions, of course, while keeping the Boot partition on the USB. Is it harmless or risky, given that USB is GPT while HD is MBR?
I wanted to do that to avoid dual-boot. Since other users are mostly using my computer with Windows, I wanted to use the USB as a sort of "magic key". No security needs, just I didn-t want to bother with dual boot the users that are using the pc most of the time.
Can I just do that with dd? Is it harmless having Boot partition on GPT disk while the rest on another MBR Hard Disk?
Thanks.

Answer 1

nomorewindows wrote:
Nukles wrote:
Many thanks for your answer!
To copy the partition can I use dd ? Because I read in another post that one must be very careful when using dd - or is it to be careful for specific dd usages?
Thanks.
Given that they are different disks, and how everything gets rearranged from one disk to another, I would just mount the disks involved and copy them over with cp/mv.  There's not really any point in exact disk duplication here. 
Linux doesn't care whether the partition table is MBR or GPT it operates as it should.  I converted from MBR to GPT in place using gdisk.  Linux didn't have to rename anything.  GPT is viable if Windows is not a problem.  So leaving Windows alone is probably the easiest with your travel media.  Why you would leave your /home and other directories to the availability to others when you already have a travel drive, might pose an unneeded situation for you. Although the travel drive will wear out quicker.
Hi,
I tried today with cp, but I have run into issues...
I have /, /boot and /home in three different partitions in the USB. I want to move / and /home into the HD into specifically created partitions, formatted with ext4.
I mounted sda8 and sda9 (my partitions on the HD for the new / and /home) into /mnt/root and /mnt/home.
Doing
cp -a /home /mnt/home
did not make any issues...
Issues started when I made
cp -a / /mnt/root
. In fact the destination partition unexpectedly filled out completely, despite being so much bigger than the source partition.
Then I realized that something (do not know yet what) had mounted my 500 GB external HD into /media/run/HD500GB so cp was copying the contents of that into the new root partition...!!! Although there is no mention of that in the /etc/fstab.
Why does it do that? If the file system of my external 500GB HD is in another partition, how come does cp copy that content, coming from the root partition, into the destination?
By the way, I unmounted the 500GB HD, and performed the command again, but... after a while it says
cp: cannot stat `/run/user/1000/gvfs`: Permission denied
Actually the first time I ran the command it stopped after a while complaining that some file systems he failed to extend due to lack of permissions... The size though was almost the same of the original partition. The directories of the new root partition were however not the same.
In the original root I had
bin boot dev etc home lib lib64 lost+fount mnt opt proc root run sbin srv sys tmp usr var
On the destination root I had
etc lib lost+found opt run sbin sys tmp usr
So my questions would be:
- Why you think the command didn t perform correctly? (I ran it after doing su - root)
- Why did it copy also the file systems residing in other partitions?
- If it copies also things in other partitions, then if I copy root, it will also copy the entire /home filesystem into the new root directory, although I had copied that already into another partition...
Can you help me?
Thanks a lot!