[SOLVED] installation crashed, cannot install grub

[oldgeek]

I tried to install 21.04 on my desktop but could not install grub. I am using a legacy install (BIOS) and manual partition. I set sda for btrfs (whole drive, no Windows for me) and got an error message after install: I needed an EFI partition. I ignored that and got another message: I needed a bootloader partition. I went back and checked that I had at least 1 mb partition free; I had two and so I chose the one before the btrfs partition and tried to change it to 'reserved BIOS boot area', but it refused to do so, with a message 'unable to satisfy all constraints on the partition'. I tried to install anyway, and got the fatal 'cannot install GRUB' error. So now I have nothing. Is it impossible to install Kubuntu without EFI? If so, how do I get EFI? Really, I don't understand these new rules for installing and never had such problems installing before.

Can someone please help me? At the moment I have no operating system and a useless computer.

[claydoh]

I think you still need a separate /boot partition with btrfs, as grub does not support this fs for booting, but I am no expert.

What sort of system do you have? most computers in the approx 10 years use EFI firmware instead of having a BIOS, though most have a 'legacy' option to emulate the BIOS mode.
The Kubuntu/Ubuntu isos are'hybrid' in the sense that they can boot in either a bios or an efi environment, and do the install accordingly. BTRFS still requires a more manual partitioning setup as I understand it

But for your use, I think you need to create a /boot partition, even on an MBR system using BIOS

[oldgeek]

My system is an old desktop, with BIOS, an i3 processor and 16GiB memory. The installation is stalled at the moment and I think you're right about the boot partition (never had to do one before). Right now I have the btrfs system on sda1 and two free partitions of 1 mb each. How do I install a boot loader partition using the installer? I tried clicking on the free partition and making it the BIOS bootloader, but it tells me I can't satisfy all the constraints and thus I can't use that partition. I must be doing something wrong. Is there another way to do this?

[claydoh]

I think you need 250mb to 500mb for the partition, and set it as /boot in the manual partitioning section.
You probably want to use gparted or KDE Partionmanager to create all the file systems, this seems to be how most people set things up for btrfs, the installer's partition tool is a bit clunky.
After making the partitions, just point the mount points at the appropriate partitions and proceed.

You need a /boot as I understand it because Grub can't read from a btrfs partition.

Those 1mb thingys are probably just dead space so to speak. Leftovers that don't quite fit, if you will.


Again, I have no hands on knowledge of things Butter-y, just some basic research so hopefully someone who has done this can chime in.

[oldgeek]

OK, here is what I did. I set up a boot loader, which is marked as sda2. The installation worked. I rebooted. That worked. I got to the OS without problem. So I decided to send the btrfs backup of my home folder to the new setup, after changing the name of the installed folder. That worked. I deleted the installed folder, to make my backup the new home folder, after changing the name, etc. Then I rebooted.

I get to the login screen. I type in my password. And it freezes. I reboot to recovery mode and try the repairs etc. Then I reboot. It freezes after I type in the password. So now I have no operating system and I don-t know what else to do, apart from buying a new computer and installing in EFI mode. Why has this been made so complicated, I do not know. I am fed up trying to do what was so easy to do before. What can I do to make my system operative again?

[jlittle]

You need a /boot as I understand it because Grub can't read from a btrfs partition.

Grub can read btrfs fine, once it's got its btrfs module loaded. (It's write support that's lacking.) On EFI this is routine.

It's the OP's BIOS making an issue. Maybe the usual 63 sector 'MBR gap' before the first partition may be too small for grub to have all the modules it needs, particularly if the btrfs uses zstd compression.

Using a separate /boot with ext2 should work, but it will need space for several linux kernels, about 110 MiB each, with 3 of these as a minimum. (Two normally, then a third while a new one is downloaded.) I'd go for 1 GiB.

[oldgeek]

I still cannot get past the login screen. I created a partition for btrfs, worked. Then I created a partition from that at 1 GiB for Grub, and that worked. Grub was marked as dev/sda1, and btrfs as /dev/sda2. I installed Kubuntu 21.04, worked. I mounted sda2 to /mnt and the external hard disk to /media, worked. I changed @home to @home_new using mv command, worked. I then used send/receive command form last snapshot on external drive of @home and sent it to /mnt. It started copying. Almost two hours later, it finished.

I synced, just to make sure. Then I unmounted both drives and restarted. I get to the login screen and it stops dead after the password. Frustration. Is it possible to use Bios to install Kubuntu, or do I have to invest in a new EFI-based computer in order to install? This problem was totally unexpected and I don't know how to resolve the situation, as there are no Linux experts where I live. Why did I ever do a clean install? I should have waited for an upgrade. This is a game-breaker for me, and I would appreciate any help from this forum on getting my computer to install Kubuntu 21.04, for as of now I have nothing.

[oldgeek]

I have finally got 21.04 installed and running fine. I re-installed like before, and checked it to make sure there were no problems in the installation. Then, instead of using the btrfs send/receive command to copy my @home back to the new install, I just simply copied and pasted the folders I wanted back, and then rebooted. This time, I got past the login screen and indeed and writing this note from the new install. Hirsute Hippo is quite nice so far. What I think MIGHT have happened is that when I had done copying I forgot to change the settings back to read-write. Could that have kept me from going past the login? I would appreciate any thoughts on this so I can anticipate potential problems when 21.10 comes out. Thanks for the help.

[jlittle]

Great, I salute your persistence.

I'd like to know your final storage configuration, and where grub lives.

I'm not sure if this is relevant to you, but it might be. If one manipulates btrfs subvolumes that are used by grub or mounted by an install, there's two places that need attention: /etc/fstab, and the grub configuration.

[oldgeek]

According to KDE partition manager, grub lies in sda1, 976 MB in length. Actually, it says 'unknown', but that's where I set the bootloader, so I guess Grub's there. BTRFS is on the rest of the desk, and is marked sda2. Did I answer your question?

[franko]

What I think MIGHT have happened is that when I had done copying I forgot to change the settings back to read-write. Could that have kept me from going past the login? I would appreciate any thoughts on this so I can anticipate potential problems when 21.10 comes out. Thanks for the help.

Yes, I believe that could be what kept you from logging in after the first successful installation. Either that, or some conflicting settings somewhere around your hidden files in your home folder, which would explain why you were able to login in recovery mode. Or even, you mentioned you were changing the name of some folder... What folder exactly? Your user's home folder has to be named exactly as the username you're using to login.
But this is all relevant to any file system, not just btrfs.

Other than that, I don't have much experience with btrfs, as I am using ext4 normally. But I have had a similar experience when I was installing Hirsute, on ext4. I also prefer booting in legacy mode, although my laptop has UEFI.
I like to setup my partitions my way, so I choose manual partitioning for installing, too. I use different partitions for / and /home, and this time around I decided to give it a little bit more space to /, and a bit less to /home. So I started a new partition table, and started to create partitions as usual: one for /, another for SWAP, and the rest for /home, where swap and /home are extended, not primary partitions. I was perplexed to see there was no option to make extended partitions any more, but I thought this should work with three primary partitions anyway, so I clicked to proceed. I got the warning about EFI, which I've never seen before, but I decided to ignore it... Than I got the other warning about Grub, same as you I guess, and that totally confused me... So before formatting I went back, looking at the new partition setup and thought: "I've NEVER had to set up a separate partition for grub, not with ext4. What is this all about?"
So nothing, I cancelled the operation and went back to see the current state of the partitions on the SSD.

From there, instead of starting a new partition table, this time I just deleted the partitions I've had on same table, and started partitioning again. Once again, there was no option for choosing between primary and extended partition, but somehow, the swap and /home were automatically set as secondary this time. So OK, this looked like what I was usually doing, except for the modified sizes, and I was happy with it. No separate partition for Grub. I clicked to go on to formatting and installing. I've got the EFI warning once again, and I ignored it once again. The Grub warning did NOT appear this time, just the warning that the disk was to be formatted. Perfect! And all worked out fine after all. Grub lives happily in sda MBR, as it always did.

After reading your post, all this looks like a bug in the manual partitioning procedure in the installer, I guess... O_o I mean, I suppose this is not your first time to be installing (K)Ubuntu on your computer, with btrfs. I am installing with manually partitioned ext4 since forever -- never had any problems. And now we've both encountered very similar strange behaviour from the installer for the first time.