Re: How to install grub onto an added drive?

[Chris Green]

On Sun, Nov 17, 2019 at 03:27:36PM -0800, Randy Goldenberg wrote:
> On Sunday November 17, 2019, Chris Green wrote:
> 
> [...]
> 
> > I want to add a new SSD to my current desktop system.  This in itself
> > isn't a major problem, I've done similar things before without
> > problems (in fact I did this already with the current small and
> > relatively slow SATA SSD that has the / filesystem on it).  The issue
> > is that I suspect the motherboard won't be able to boot from the new
> > NVME/PCIe SSD so I'm aiming to have a small, bootable drive to just
> > provide the boot files and have everything except for /boot on the
> > new, fast, SSD.
> > 
> > So, I can move all the required OS files to the new hard disk but how
> > do I get grub installed on whatever I have as a 'small' boot disk?
> 
> Someone willing to help would need to know if you're using legacy BIOS
> booting, or UEFI.

Ah, oops, yes a rather basic piece of information.  It's traditional
BIOS.  Doesn't the BIOS need to be 'UEFI aware' if one is going UEFI?


> > 
> > Basic questions:-
> > 
> >    Presumably the disk where the /boot filesystem is has to be marked
> >    bootable using fdisk.
> 
> That depends on how you're booting.  Legacy, or UEFI?

Legacy.


> > 
> >    How do grub-install and grub-mkconfig relate to each other?  Which
> >    do I run first?  Do I need to run both?  What do I need to tell
> >    them (parameter-wise)?
> 
> grub-install installs grub.  grub-mkconfig writes a grub.cfg file, read by
> grub at boot time.  Parameters are explained in "info grub".

Yes, I have worked through "info grub" quite a bit, the details are
there but there's not much overview as it were.


> > 
> >    Is there anything else I need to do?
> > 
> >    I guess I need to run grub-install and grub-mkconfig on the system
> >    as I want it configured, i.e. with the new/small disk waiting for
> >    grub to be installed on /boot.  So, this feels a bit risky as,
> >    until grub has been installed there the system won't [re]boot.
> >    What's the best way to make sure I have a 'get out' if it all goes
> >    pear shaped?
> 
> Back up your system.
> 
> https://www.clonezilla.org/

My data is well backed up, if it all goes *really* pear shaped I will
simply re-install the OS from scratch and restore all my data.  I was
hoping for 'intermediate' disaster recovery to get back to a bootable
system without having to restore everything.

> > 
> > Yes, I know that question about grub-install and grub-mkconfig seems
> > rather naive but I have to say none of the tutorials, man pages or
> > other help that I could find actually clarified this.
> 
> See "info grub".
> 
See above! :-)


> Your description of your situation suggests that you are using legacy BIOS
> booting.  If that is the case, in the absence of limiting circumstances, I
> strongly recommend moving to UEFI.
> 
As I asked above, does the BIOS have to be UEFI aware to move to UEFI?

-- 
Chris Green