My question is simple. I currently have Windows 7 (64-bit) installed on a SSD MBR partition. I also have a 3TB HDD that I am splitting between extra Win-7 storage and what will hopefully be an Ubuntu partition. The catch is that since the HDD is 3TB, it must be formatted as GPT. Furthermore I would like to use the GRUB boot loader to give me the option of booting into Windows or Linux and have it reside on my SSD to take advantage of the speed.

If it matters, I plan to install Ubuntu via USB-flash drive.

Should this be as simple as installing Ubuntu to a partition on my 3TB HDD drive and setting the bootloader device to install to my SSD? I would like to know the probable results before attempting this.


I have XP on one MBR drive and have had Ubuntu on gpt drives since 10.10, but not on a large drive like yours. There were (are?) issues with very large / (root) partitions. So my suggestion is to keep Ubuntu / to 25GB and then have separate /home and your NTFS shared data partition. Also better to have / near the beginning of drive, some BIOS have issues with / beyond 100GB on drive, but seems to be more an issue with external USB hard drives, BIOS and grub (not sure which).

I would probably keep the Windows boot loader on the Windows drive and grub2 on the Ubuntu drive. But you also could install grub to both.

You do have to use Something Else or manual install to get the option on where to install the grub2 boot loader. All default installs just install to sda (assumes BIOS set to boot sda). Then change BIOS to boot from drive you installed grub into.

If drive may ever be used with a UEFI system in near future I might reserve 300MB space at beginning of drive for an efi partition. Per UEFI spec it is supposed to be first, but Windows often makes it second or third but still near beginning of drive. Adding that when drive is full might be an issue.

For grub to install correctly to gpt drive booting in BIOS mode, you will have to have a tiny 1 or 2 MB unformatted partition with the bios_grub boot flag. That can be anywhere on the drive.

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  • I mostly agree with this, but have a couple of minor corrections/additions. First, the EFI System Partition (ESP) need not be the first partition or near the start of the drive. The EFI spec says "UEFI does not impose a restriction on the number or location of System Partitions that can exist on a system." (2.3.1 spec, p. 492.) The location of the BIOS Boot Partition (identified by the bios_grub flag), though, can be important; some BIOSes can't read it from beyond the 2TiB mark (or even earlier on very old computers). Thus, I'd put it early on the disk. – Rod Smith Nov 13 '13 at 0:02

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