Please help me with partition regarding uefi multi-boot ...

mangya · 06-29-2016, 09:01 AM

Hello

I want install Ubuntu 16.04 as my default OS and CentOS 7 as advanced learning OS. I have a hdd of 1TB with GPT partitioning scheme.

I partitioned as follows:

Code:

sda1 500M EFI
sda2 8G   Swap
sda3 15G  ext4 ## For Ubuntu
sda4 15G  xfs  ## For CentOS
sda5 200G ext4 ## Home for Ubuntu
sda6 200G xfs  ## Home for CentOS

I installed Ubuntu on sda1 (/boot/efi), sda3 (/), sda5 (/home) and then installed CentOS on sda1 (/boot/efi), sda4 (/), sda6 (/home).

Following is happening:

I boot to CentOS grub2 menu, can boot to CentOS but when I select Ubuntu option, it says cannot find Ubuntu's kernel to boot.
I switched OSs, installed first CentOS and later installed Ubuntu. Same thing, i can boot to Ubuntu but cannot boot to CentOS. Same error message.
I tried os-prober and updated grub2, but still the same problem - cannot find kernel.

Please guide me on how I should solve this. Googled, but couldn't find any answers (all solutions are for dual boot with Windows only, no linux-linux dual boot). Is this even possible - multi-booting two linux distros in efi? Worked when using mbr though, but I don't want to use mbr.

Is there any other way I should partition my disk?

Thank you.

onebuck · 06-29-2016, 09:47 AM

Hi,

Look at; UEFI - Ubuntu Guide

Be sure too look at; boot-repair -- Ubuntu Community wiki

Plus you should scroll down within this thread to check out similar threads for possible help.

Hope this helps.
Have fun & enjoy!

Keruskerfuerst · 06-29-2016, 09:48 AM

You should always add a /home partition, since when a reinstallation is done, the /home partition can be used without formatting the /home partition.

Further, you can add a partition for /var and /tmp.

And just use ext4 for all parititons, since ext4 is the fastest linux filesystem.

The error when trying to boot Centos, is the missing entry in grub.cfg for Centos.

onebuck · 06-29-2016, 10:03 AM

Hi,

I see no harm in using a partition for /home. But you should not mix /home between different Gnu/Linux installs since that will certainly create issues. I like to configure my Slackware installation with;

Code:

# cat /etc/fstab

/dev/sda2        swap             swap        defaults         0   0
/dev/sda5        /                ext4        defaults,noatime,discard         1   1
/dev/sda6        /home            ext4        defaults,noatime,discard         1   2
/dev/sda7        /usr             ext4        defaults,noatime,discard         1   2
/dev/sda8        /var             ext4        defaults,noatime,discard         1   2
/dev/sda9        /tmp             ext4        defaults,noatime,discard         1   2
#/dev/sdb2        /mnt/win7        ntfs-3g     fmask=111,dmask=000 1   0
/dev/sdb1        /mnt/win7        ntfs-3g     fmask=111,dmask=000 1   0

#/dev/cdrom      /mnt/cdrom       auto        noauto,owner,ro,comment=x-gvfs-show 0   0
/dev/fd0         /mnt/floppy      auto        noauto,owner     0   0
devpts           /dev/pts         devpts      gid=5,mode=620   0   0
proc             /proc            proc        defaults         0   0
tmpfs            /dev/shm         tmpfs       defaults         0   0

Allocated as;

Code:

# fdisk -l /dev/sda

Disk /dev/sda: 256.1 GB, 256060514304 bytes
255 heads, 63 sectors/track, 31130 cylinders, total 500118192 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x2cad8de1

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    41945087    20971520   83  Linux
/dev/sda2        41945088    46241791     2148352   82  Linux swap
/dev/sda3        46241792    88184831    20971520   83  Linux
/dev/sda4        88184832   500118191   205966680    5  Extended
/dev/sda5        88186880    94478335     3145728   83  Linux
/dev/sda6        94480384   115451903    10485760   83  Linux
/dev/sda7       115453952   136425471    10485760   83  Linux
/dev/sda8       136427520   138524671     1048576   83  Linux
/dev/sda9       138526720   146915327     4194304   83  Linux

Size for each;

Code:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda5       2.9G  354M  2.4G  13% /
/dev/sda6       9.8G  5.5G  3.8G  60% /home
/dev/sda7       9.8G  8.1G  1.2G  88% /usr
/dev/sda8       976M  398M  512M  44% /var
/dev/sda9       3.9G  704M  3.0G  20% /tmp
tmpfs           7.8G  141M  7.7G   2% /dev/shm
/dev/sdb1        98G   57G   42G  58% /mnt/win7
/dev/sdc2        92G   53G   35G  61% /mnt/sdc2
/dev/loop1      2.6G  2.6G     0 100% /mnt/sde

I use external USB drives for local storage so as not to load my SSD.

Hope this helps.
Have fun & enjoy!

plasmonics · 06-29-2016, 12:11 PM

I don't see anything wrong with your disk partitioning scheme. On UEFI/GPI systems, os-prober sometimes gets it wrong. Is CentOS your primary boot loader? I am less familiar with ubuntu. Perhaps someone else could help with that. Assuming CentOS, insert the following stanza in Cent's /etc/grub.d/40_custom:

Code:

menuentry "Ubuntu" {
  insmod part_gpt
  insmod chain
  insmod ext2
  set root='(hd0,gpt1)'
  chainloader /EFI/ubuntu/grubx64.efi
}

Then remake the CentOS grub.cfg file using

Code:

grub2-mkconfig -o xxxxxxx

You need to check where grub.cfg is stored. Usually for Fedora-based distros, it is in /boot/efi/EFI/******/grub.cfg
Find out where yours is located and reboot. If all goes well, your should see Ubuntu from Cent's grub menu.

mangya · 06-29-2016, 12:15 PM

Quote:

Originally Posted by plasmonics

I don't see anything wrong with your disk partitioning scheme. On UEFI/GPI systems, os-prober sometimes gets it wrong. Is CentOS your primary boot loader? I am less familiar with ubuntu. Perhaps someone else could help with that. Assuming CentOS, insert the following stanza in Cent's /etc/grub.d/40_custom:

Code:

menuentry "Ubuntu" {
  insmod part_gpt
  insmod chain
  insmod ext2
  set root='(hd0,gpt1)'
  chainloader /EFI/ubuntu/grubx64.efi
}

Then remake the CentOS grub.cfg file using

Code:

grub2-mkconfig -o xxxxxxx

You need to check where grub.cfg is stored. Usually for Fedora-based distros, it is in /boot/efi/EFI/******/grub.cfg
Find out where yours is located and reboot. If all goes well, your should see Ubuntu from Cent's grub menu.

Thanks I'll try your solution.