GPT partitioning

eco_bach · 01-04-2017, 09:45 PM

Hi
3rd time re partitioning my 1TB SSD so hoping to get it right.
Learning but still many questions

Because my system has UEFI firmware and already have a SSD dedicated to Windows my understanding is that I MUST have a UEFI boot partition on my 2nd SSD dedicated to Linux.
And if using GPT partitioning in addition it needs to have the 'boot' flag set.

My first point of confusion is conflicting device I am reading about GPT vs MBR-msdos partitioning.

At ubuntuforums here under Two Drive Installs>Partitioning it states
https://ubuntuforums.org/showthread.php?t=2147295

Quote:

With UEFI, gpt partitioning is (almost) required. If multiple drives all bootable drives need to be gpt and best if data drives are also gpt in case later you want to make it bootable. With gpt there is no primary, extended, logical partitions as in MBR(msdos) nor the 4 primary partition limit.
You can only have one efi partition per drive and with gparted you use the boot flag to assign it as the efi partition. No other partitions can have boot flag. Only if booting in BIOS mode with Ubuntu on gpt partitioned drive, you need a bios_grub partition.
Windows will only boot in UEFI mode so you cannot install Windows to gpt drive unless booting with UEFI.

but this partition guide over at ubuntu-mate.community seems to indicate using MBR partitioning
ubuntu-mate.community
see Part 4: Create a UEFI boot partition. + swap + root + home partitions.

Which is right?
Why is GPT partitioning recommended for UEFI?

syg00 · 01-04-2017, 11:01 PM

Use gpt regardless of (U)EFI - it will (eventually) make your life easier.
As you seem confused enough, don't create an efi partition on any disk other than the boot (Windows in your case) disk. Simply use the one already present. Most Linux installers recognise this implicitly.

hazel · 01-05-2017, 03:15 AM

It's simple. A UEFI chip working in native mode can't boot from a DOS disk. DOS disks have their bootloader in the mbr and the UEFI boot mechanism doesn't look there. It only looks in the efi system partition.

You can (at the moment) use a UEFI in compatibility support (legacy) mode with a DOS disk but who knows how long that mode will continue to exist?

Rickkkk · 01-05-2017, 02:30 PM

Hi again eco_bach ...

As mentioned above, GPT (GUID Partition Table) is progressively replacing the old MBR (Master Boot Record) partition table. Also as mentioned above, GPT does away with the 4-primary-partition limit of MBR. Most new firmware is UEFI instead of BIOS based and, again, as mentioned above, UEFI will probably stop supporting MBR-based partitioning down the road. So - short answer - go GPT. That said, I don't see the conflicting advice in your above example - Ubuntu is just suggesting a typical partitioning scheme. If you really do have 2 separate physical hard drives (SSD or otherwise), and want to be able to boot from either, you need to have an ESP (EFI System Partition) on each one.

Partitioning as a subject can be a little daunting at first - judging from your 2 recent posts, I am guessing you are fairly new at it. I suggest reading up on it, but feel free to post other questions if needed.

Cheers,

fpmurphy · 01-05-2017, 09:15 PM

Quote:

Originally Posted by eco_bach

Hi
Because my system has UEFI firmware and already have a SSD dedicated to Windows my understanding is that I MUST have a UEFI boot partition on my 2nd SSD dedicated to Linux.

As an FYI, you do not actually need a separate "boot partition" (actually called an ESP - EFI System Partition) on your second SSD. You can add the appropriate files to the existing ESP on your first SSD. Can be a bit complicated to correctly setup as many current Linux Distributions that support UEFI-booting expect to have the ESP to themselves.

Rickkkk · 01-05-2017, 11:14 PM

Quote:

Originally Posted by fpmurphy

As an FYI, you do not actually need a separate "boot partition" (actually called an ESP - EFI System Partition) on your second SSD. You can add the appropriate files to the existing ESP on your first SSD.

@fpmurphy: ... this is good to know. My limited experience so far with UEFI had led me to understand that each physical bootable drive required its own ESP - thanks for the info !

Cheers :-)