I have a notebook which has two drives: one is an SSD and the other is an HDD. It also currently has both Windows 10 (SSD) and Windows 7 (HDD): I want to remove Windows 7 and install Debian 10. As I'd like it to boot fast, it would be a great idea to put all the system files required for boot in the SSD and the other files in the HDD (as the SSD has not got so much space (~20 GB left)). So I thought to set up Debian installation in this way:

  • One partition on the SSD in which I mount the /boot directory (~2GB)
  • One partition on the HDD in which I mount the / directory (root) (~90GB)
  • One partition on the HDD in which I mount the /home directory (~150GB)
  • One partition on the HDD as a swap area (~12GB - my RAM size is 12GB)

The problem is that, by looking in the Disk Management tool in Windows (screenshot below: the HDD is HITACHI and the SSD is KINGSTON: please note that the HDD begins with an EFI partition), the SSD and the HDD use two different partition tables: the former uses MBR and the latter uses GPT. I must admit that I don't know well the difference between EFI/UEFI and legacy systems and I don't know how to specify to the debian installer which one to use. Could you please tell me whether the aforementioned partition scheme would work and if I need to take some precautions regarding the GPT/MBR and the UEFI/EFI/BIOS problem?

enter image description here

Thanks in advance

  • 1
    Windows only boots from MBR(msdos) partitioned drives in BIOS boot mode and only in UEFI boot mode from gpt partitioned drives. Best to reinstall Windows in UEFI boot mode to gpt drive. Most Linux will boot from gpt drive in either BIOS or UEFI if correct supporting partition. BIOS needs bios_grub for grub to install, or ESP - efi system partition for UEFI boot. But grub will only dual boot other installs in same boot mode. Once you start booting, you cannot switch or grub only boots other installs in same boot mode.
    – oldfred
    Aug 28, 2019 at 15:19
  • +1; you might also read these excellent explanations that helped me a lot back then: rodsbooks.com/efi-bootloaders (PS: spreading installation over both drives in a laptop this way seems inoptimal to me, any dead drive will render it unbootable; and /boot is not about actually booting fast, it's just a bootloader, a kernel and an initrd with more or less linear read-only access) Aug 29, 2019 at 5:58
  • @oldfred Unfortunately, reinstalling Windows 10 is not an option I have. I need to do everything without reinstalling it. However, I read somewhere that it is possible to convert MBR to GPT (and vice versa): can I convert the HDD partition table to MBR (after having removed Windows 7) and then install Debian 10? Is this recommendable?
    – LuxGiammi
    Aug 29, 2019 at 10:21
  • 1
    @MichaelShigorin the reference you've given me is amazing! I'll print it out and read it. Thanks for pointing out that it would be inoptimal: so I should install everything (except maybe my own /home directory) on the SSD to make it retrieve files needed for the entire boot process faster (I'm sorry if my terminology is not precise: by boot I mean the time that passes from the time when I hit 'Enter' to choose the OS to the time when the OS asks me for my login information)?
    – LuxGiammi
    Aug 29, 2019 at 10:32
  • 1
    Its either MBR or gpt unless you use a hybrid configuration which is not recommended. Hybrid was used on older UEFI Mac when Windows was BIOS. rodsbooks.com/gdisk/hybrid.html. I suggest a 25GB / (root) partition on SSD and /home and/or data partitions on HDD.
    – oldfred
    Aug 29, 2019 at 13:52


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