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My system is partitioned this way:

hdda 500 giga (/dev/sda) ssd 20 giga (/dev/sdb)

/dev/sda

/boot(300 mega) /home(remaining space)

(/dev/sdb)

/ (14 giga main system with ubuntu 14.04 x64)

/ (7 giga to test another O.S. versions , actually with ubuntu 14.04 )

swap (2 giga)

After install ubuntu 14.04 to (/dev/sdb) second partition(7 giga) i suppose grub has been replaced . The problem is even after upgrade kernel to last version using my main system ((/dev/sdb 14 giga)it doesn`t go automatically to last version after reboot even choosing with grub customizer , just if reboot and go to second system installed and use grub customizer there

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    Better not to have separate /boot, you cannot share it anyway, have to maintain it separately. And if you houseclean it regularly it is not large. And just put test install on HDD, will not be quite as fast but it is just for testing. If you have 4GB of RAM or more I would also have swap on HDD, as you will never use it. You can have different boot loaders in each drive. I normally keep grub on same drive as install. So my SSD has my working system's MBR or now efi and my hard drive has last test install as I usually have several test installs on HDD.
    – oldfred
    Mar 28, 2015 at 16:27

1 Answer 1

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With two installs you have to normally do two updates. Whichever system's grub is in MBR must be booted and sudo update-grub run to find newer kernel in second install.

But since you have two drives, put main working install's grub into the MBR of sdb. And keep test install's grub in MBR of sda. When you install grub defaults to sda. Better to use Something Else and on partitioning screen change to MBR of same drive.

You can boot into install in sdb and install grub to the SSD's MBR. Then change BIOS to boot SSD.

sudo grub-install /dev/sdb
sudo update-grub

If you can only boot from sda, then just change /dev/sda.

But if you originally installed grub to sda, it remembers that setting for reinstall on major updates. So you also need to reset that:

To see what drive grub2 uses see this line (BIOS only, not UEFI) - grub-pc/install_devices:

sudo debconf-show grub-pc  

It will show drive model & serial number to see drive info

sudo lshw -C Disk -short 

to get grub2 to remember where to reinstall on updates:

sudo dpkg-reconfigure grub-pc 

Enter thru first pages,spacebar to choose/unchoose drive, enter to accept, do not choose partitions

You can also avoid the double update by manually adding your own boot stanza in 40_custom and directly boot partition or link to most current kernel.

https://help.ubuntu.com/community/MaintenanceFreeCustomGrub2Screen

UEFI systems do not use grub-pc but grub-efi-amd64 if 64 bit or perhaps signed versions. So all of above is only for BIOS based systems.

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  • Do you mean UEFI enabled on BIOS ? Because my system has not uefi enable . And also my system has an hybrid storage (SSD + HDD)
    – E_Angel
    Mar 28, 2015 at 16:42
  • You seem to show just BIOS based installs, so UEFI is not a consideration. It just is the commands posted are only for BIOS based installs. So others looking at them may not work if an UEFI install as commands are different. But even systems with UEFI capable hardware may install in BIOS boot mode or CSM.
    – oldfred
    Mar 28, 2015 at 16:44
  • As an hybrid storage there isnt an option to change Boot in BIOS , except for external drives, cds , usb ,etc . Then if i do: sudo grub-install /dev/sdb would it work ?
    – E_Angel
    Mar 28, 2015 at 16:47
  • If not then the only choice is to install grub to sda. Some systems still let you boot from a SSD used in Ultrabooks. If drive seen as a separate drive I would think it should be bootable, but BIOS may not be configured for it. Do you have latest BIOS from vendor. Are drives set for AHCI, not IDE nor RAID?
    – oldfred
    Mar 28, 2015 at 17:02
  • i have checked BIOS version and there is no new version , so i think its not possible to boot and also not install grub on sdb. Could you update answer to how to install grub and make system recognize it as boot choyce ?
    – E_Angel
    Mar 28, 2015 at 20:22

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