Two Linux (Linux-learner) Backup-computer partitioning...

[Mike Krall]

I also suggest using gpt.
But with BIOS boot on gpt you need a tiny 1 or 2MB unformatted partition with the bios_grub flag.

I did that starting back in 2010 before PCs had UEFI. Windows required MBR for BIOS boot, but Ubuntu worked from gpt.
Later when PCs started having UEFI, I made first partition an ESP for UEFI boot (even though I did not yet have UEFI) and used bios_grub for booting. But then could move drive to newer system, reinstall grub can convert to UEFI without having to totally redo drive.

I've been trying to reconcile a couple of questions pertaining to 'oldfred' post. The whole thing, but pointing to Blue.

And... looking at Grub Manual 4.4 - BIOS installation: https://www.gnu.org/software/grub/ma...S-installation Specific: Last para. MBR and GPT from "but it can also be used on BIOS platforms..."... then on.

And... the Arch Wiki Partitioning page (charts 3/5's down): https://wiki.archlinux.org/index.php/Partitioning ... third chart... "BIOS/GPT example layout".

The three look to be saying the same but I don't have a way of telling for sure.

And then... if I've got this right... I don't need the 'parted' code in GRUB 4.4 because the installer has the same facility built in... does what the code would do... Is right?

And then... I've gotten confused with what GRUB-thing needs to happen with following OS install. Have seen "install to ' / ' " ... ignore the question... do one or the other (or another) then goto first install (OS with GRUB in small BIOS_grub flag partition) and code ????????. I just keep looping back on myself with this. In the end, I'd like to have a boot screen come up and show both OS. What's the move of highest likelihood for that with GRUB and the other OS?
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A thing I wonder: Using GPartEd to partition prior to installing... blanking out Windows 7 ("Create New Partition")... Because of the disk/BIOS structure (( from Belarc Advisor: Boot Mode: Legacy BIOS in UEFI (Secure Boot not supported), and I should have put that in at the beginning of this thread ))... Will there be a remnant area at disk front -- the "at least 31 KiB (63 sectors) from the start of the disk..." (from Grub 4.4)? If yes, does it matter in relation to 'oldfred' "tiny 1 or 2MB unformatted partition with the bios_grub flag"? If yes, is there an approach with GPartEd that would erase that? If yes, how?

Is that enough?

Mike

[oldfred]

The 63 sectors is before the first partition with old systems XP era & maybe early Windows 7. It now is 2048 for alignment with new systems.
Grub in BIOS mode installs to MBR, but MBR is so tiny it needs more code and uses the space after the MBR for core.img. Windows also uses that space for some security info like flexnet. Used to create conflicts but grub works around that.
Windows also installs its boot loader to MBR in BIOS, but then has more code in PBR, partition boot sector & its boot partition or main install partition whichever has boot flag.

Windows has required UEFI/gpt since release of Windows 8 in 2012. Windows 7 can be installed in UEFI mode, but usually was BIOS/MBR. Large customers still wanted BIOS mode with newer hardware so even Windows 10 can be installed in BIOS mode. There is some discussion that new systems in a year or two will eliminate the BIOS mode, but old hardware would not be affected.

If only using one drive, you have to install all systems in same boot mode. And Windows sets rule.
Windows requires MBR partitioning with BIOS boot.
Windows requires gpt partitioning with UEFI boot.
Ubuntu does not seem to care, but incorrectly lets you install Ubuntu in UEFI mode to MBR drive and then conflicts with Windows. If no Windows on drive it would be ok, but gpt is better than MBR, so no reason to use MBR unless you have to have Windows in BIOS boot mode.

If using newer gpt partitioning there is no space after MBR, so a BIOS install of grub needs space for core.img and has to have the 1MB unformatted partition bios_grub.
With gpt Windows has to have the system reserved partition which is where is puts the info it used to have right after MBR. So now no conflicts with grub & Windows.

Use Windows tools for Windows & use Linux tools for Linux is best advice. Windows will not see nor work with Linux and while some third party Windows tools will see the Linux partitions better in almost all cases to use Linux tools.

If you have newer UEFI based hardware better to have both Windows & Ubuntu in UEFI boot mode. A few have so many issues with older UEFI implementations they do stay with BIOS/CSM/Legacy boot, but that is really the hardware vendor's UEFI or user preference. UEFI also has more settings since it also can be BIOS and some systems need multiple settings to install Ubuntu.

[Dennis N]

Your second link (to arch linux wiki) is broken - no charts there.

Here is example of bios grub partition needed on GPT-partitioned disk when used for bios install. 2 MB was specified as the size, and bios_grub flag was set. The partition editor in the installer seems to be the same as the stand-alone gparted. In fact, in my last install, I think I used the installer's partition editor to do the work. It works. As you can see, this setup is not limited to 4 (primary) partitions as MSDOS partitioning would be.

Model: ATA Samsung SSD 860 (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  3146kB  2097kB                     bios_grub
 2      3146kB  44.0GB  44.0GB  ext4
 3      44.0GB  296GB   252GB                      lvm
 4      296GB   401GB   105GB                      lvm
 5      401GB   469GB   68.2GB                     lvm

(The disk is sdb, because it was added later and changed to be the first boot disk in BIOS.

[oldfred]

I started conversion to gpt in 2010 and had to have a bios_grub. Grub just would not install without it. Windows XP then was separate MBR drive.
Then in 2012, as new hardware was UEFI, I started to add both an ESP & the bios_grub partitions to all new drives and larger flash drives, even though still BIOS system. I figured I could then move drive to new UEFI system without major re-partitioning. Most of my flash drives are full boot installs, but really for emergency boot and backup data. Now I do not add bios_grub anymore.

Oldfred's partitions with new NVMe Feb 2020 UEFI
https://ubuntuforums.org/showthread....5#post13934695
Oldfred's partitions Dec 2015 has ESP & bios_grub
http://ubuntuforums.org/showthread.p...3#post13404413

[Mike Krall]

Your second link (to arch linux wiki) is broken - no charts there.

Fixed link, 'Dennis N'... checked it for function.

Be back later... working on house building.

Mike

[Dennis N]

The three look to be saying the same but I don't have a way of telling for sure.

Yes, they agree. In the "BIOS/GPT example layout", beside the bios boot partition, you need a partition to serve as / for the installation; if you are using Ubuntu only (no multi-boot), you don't need the swap partition because Ubuntu will create a swap file in it's / partition. Nor do you need the Home partition. If you install Manjaro or Fedora, I'm not sure they can use a swap file - a swap partition may be needed.

The information doesn't cover LVM setup at all, so I will skip that.

Summary:

bios-boot-partition + ext4 partition for / is enough for standard (non LVM) Ubuntu install in BIOS mode using GPT. A 'Home' partition is optional.

Unencrypted installs (standard and LVM) don't need a /boot partition. This is so for Ubuntu flavors, Manjaro varieties and Fedora at least.

[Mike Krall]

Thanks 'oldfred'... Thanks 'Dennis N'...

I think I'm coming clearer on this... lots of reading tonight.
-----------------------------------------

There won't be any Windows 7. Will put in Linux Lite, then Ubuntu MATE... both /, /home and a swap partition. Will GPartEd all the partitions from Linux Lite, then install it... then, etc.

In the Belarc Advisor Report, besides "Boot Mode: Legacy BIOS in UEFI (Secure Boot not supported)", I saw this : "UEFI: Insyde Corp. 1.50 11/23/2011" The Win. 7 is definitely partitioned MBR... Windows says so... GParted says so... "sudo parted -l"says so. There is NO CSM/Legacy switch in BIOS/firmware... I've looked and looked. I'm wondering, if Windows weren't in the machine, if it becomes a GPT/UEFI set up. A mention by 'oldfred' in one of the links given speculates a thing like that... a switch.

With MBR partitioning... 1-2 MiB boot_grub... extended... /... /... swap... /home... /home

Could leave 'unallocated' of size for EFI_boot between boot_grub and extended... could just make the EFI_boot partition in that position and let the OS-es sort it out. Potential problem I see with that is Linux Lite is not "modern" with GPT/UEFI. They have two different install versions... most up to date (4.8) is MBR... If a person needs to do GPT/UEFI, the procedure is to install 4.2, then immediately run an upgrade to 4.8. The upgrade is more a big version change rather than say, an Ubuntu 16 to Ubuntu 18 upgrade. At the end of which Linux Lite is then fine with UEFI.

Seems like going the BIOS/GPT route with the 'unallocated' space is sounder right now. I'll be doing upgrades in less than a year... about when Ubuntu MATE 18.04 looses support (and about when 20.04 will be 20.04.1 or .2) and Linux Lite has some time in with it's Ubuntu 20 base. May have to redo to UEFI then, but ???.

Mike

[oldfred]

I would check if you have a UEFI/BIOS update.
Often the early UEFI implementations needed updates as vendors were also fixing things.

If not an gpt drive, you have to in gparted choose to change it. That will totally erase drive.
You can also use gparted but must change default partitioning first.
Select gpt under device, advanced over msdos(MBR) default partitioning before starting.

If data is well backed up, but you want to keep a partition, you can convert MBR to gpt.
Converting to or from GPT - must have good backups.
http://www.rodsbooks.com/gdisk/mbr2gpt.html

[Mike Krall]

I would check if you have a UEFI/BIOS update.
Often the early UEFI implementations needed updates as vendors were also fixing things.

If not an gpt drive, you have to in gparted choose to change it. That will totally erase drive.
You can also use gparted but must change default partitioning first.
Select gpt under device, advanced over msdos(MBR) default partitioning before starting.

If data is well backed up, but you want to keep a partition, you can convert MBR to gpt.
Converting to or from GPT - must have good backups.
http://www.rodsbooks.com/gdisk/mbr2gpt.html

I seem to get confused easily...

Blue: I've checked every way I could find... looking at firmware and available updates... Windows in Windows... Windows in Linux. Not seeing UEFI/BiOS update. Windows (Disk Management...Disk 0... only one disk) won't let me convert to GPT and that is just one Windows in Windows approach with that conclusion.

I understand I can maybe do this through GPartEd (or possibly your link to Rod Smith... he's always tough for me to follow... get left in the dust a lot). I'll try going to GPartEd site and see what they say about step-by-step to convert.

Still have this nagging wonder if somewhere in this mid-2012 machine is an inherent lock to MBR and/or ??? Wonder if Belarc Advisors "Secure Boot Not Supported" is an indication of this.

Thanks 'oldfred'...

Mike

[oldfred]

Windows 7 supports UEFI, but does not support UEFI Secure Boot.

You can look into your UEFI/BIOS and see version number, then look online for your vendor's support site and see if there is an update. Since pretty old, it may not have a recent update, but may have something newer with some fixes.

Attached some old screen shots from gparted. Newer will look a bit different, but is same function.
You have to click on device at top menu first, before anything else and choose gpt. With small drives it defaults to MBR. Installer in BIOS mode defaults first to whatever drive is, and uses MBR if smaller drive in BIOS mode.
In UEFI mode it uses gpt, unless drive is MBR. It really should not allow UEFI on MBR drives, but does.