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I have a ThinkPad T420 laptop, with two disks.

  • SSD: 128GB, GPT (disk1)
  • HDD: 5400 rpm, 500GB, MBR (disk2)

I need to run 2 OSs on this laptop: Windows 10 + Ubuntu 16.04, so I decided to:

  1. Install both, Windows 10 and Ubuntu 16.04 in the SSD disk (disk1). It's a GPT disk, and contains partitions for both OSs. It's working fine.
  2. Install everything not considered "part of the OS" in the other drive (disk2), for both OS. So, I've created 2 partitions: ext4 and ntfs. Moved the home folder of Ubuntu 16.04 to the ext4 partition. No problem at all.

Ubuntu runs fine with this configuration. The problem is with Windows 10. It won't start (stuck in the loading windows splash screen). If I delete the ntfs partition of disk2, it runs. Then, I try to create again the partition in disk2, with native disk management tool and with EaseUS Partition Manager. Not working. It hangs, and I need to fix things again from Ubuntu with GParted.

Questions:

  • Can't I have a gpt disk and a mbr disk in the same machine? Can't Windows 10 and Ubuntu handle that? Ubuntu works fine with it, but Windows is crashing.

  • If my problem is not related with both disks having different partition schemas (GPT and MBR), what could be the problem? Why Windows can't handle both disks?

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2 Answers 2

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Ok, I fixed it by repartitioning my second disk using EASEUS Partition Manager from Windows, and then reinstalling Ubuntu. Looks like Windows 10 didn't like the way I created partitions from GParted.

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In the spirit of Stack Exchange's standard of having one actual question per Stack Exchange question, I will answer one piece of your multi-question question. (I generally try to answer all pieces, but since I have one answer readily available, I'll give you what I have right now.)

Can't I have a gpt disk and a mbr disk in the same machine?

You can't have both GPT and MBR.

Correction: If you have GPT, you must have an MBR. That is part of the GPT standard. If you don't have an MBR with some specific data, then you aren't following the GPT standard. However, when a system is using GPT compatibility, the data in the Protective MBR is untrusted and ignored, and is therefore useless. (This Protective MBR says there is just one giant partition. GPT-aware boot processes will ignore that useless data, and rely on the information stored in another location on the disk, where the GPT standard specifies such information to be.) See: Wikipedia's page on GPT: “Protective MBR” section.

The following Wikipedia section (Wikipedia's page on GPT: “Hybrid MBR” section) indicates possible usage of both GPT and a special type of MBR. The boot code contained in this MBR is “modified to recognize GPT partitions”. So even that isn't a traditional MBR implementation. It is a custom MBR implementation designed to work with GPT. Your safest approach is likely to consider this to be not-very-standard.

It wouldn't surprise me at all if an operating system sticks to more common/traditional standards. Therefore, the Hybrid GPT's special MBR could easily be wiped out, as a standard process.

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  • I think the OP meant two disks: one with GPT, the other with MBR only. Your answer covers "GPT+MBR on single disk" topic. Or am I getting it wrong?
    – Kamil Maciorowski
    Jul 6, 2016 at 16:36
  • @KamilMaciorowski : I think you're right. I was talking about having both on a single disk. However, I will leave my answer in place, because I think the info may still be valuable; this may be a cause of some of the experienced problems (when Original Poster of Question makes changes to the MBR, the GPT boot code may not be recognizing that.)
    – TOOGAM
    Jul 6, 2016 at 16:53

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