[TriLUG] grub2-install fails with error: unknown filesystem

[Lee Fickenscher via TriLUG]

Ron,
Thanks for the reply.
These appear to be grub legacy commands, are they still valid with grub2?

-Lee

On Thu, Nov 9, 2017 at 11:05 AM, Ron Kelley <rkelleyrtp at gmail.com> wrote:

> I have done this in the past when I converted from non-raid to raid.  Hope
> it works for you:
>
> Grub:
> device (hd0) /dev/sda
> device (hd1) /dev/sdb
> root (hd0,1)
> setup (hd0)
> root (hd1,1)
> setup (hd1)
>
>
> > On Nov 9, 2017, at 2:00 PM, Lee Fickenscher via TriLUG <
> trilug at trilug.org> wrote:
> >
> > Greetings luggers,
> >
> > I've been fruitlessly googling the issue over the last couple of days and
> > I'm hoping that someone has encountered and triumphed over this issue...
> >
> > Issue:
> > Trying to install grub to the mbr of one of a dmraid1 mirror fails
> > with error: unknown filesystem.
> >
> > The preamble:
> > We have a CentOS7 server with OS disks in mdraid1 partitioned thusly:
> >
> > --------------------------------------
> > $ sudo fdisk -l /dev/sda
> >
> > Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 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 label type: dos
> > Disk identifier: 0x00000000
> >
> >   Device Boot      Start         End      Blocks   Id  System
> > /dev/sda1            2048    67110911    33554432   fd  Linux raid
> > autodetect
> > /dev/sda2   *    67110912    69208063     1048576   fd  Linux raid
> > autodetect
> > /dev/sda3        69208064   976773119   453782528   fd  Linux raid
> > autodetect
> > --------------------------------------
> >
> > sda1 is swap
> > sda2 is /boot
> > sda3 is LVM root
> >
> > During setup we make sure that the MBR is written on both raid members so
> > we can always boot and previously haven't had a problem.
> > We had a drive fail so the drive was replaced, partition table written,
> and
> > raid arrays synced. All was good until I tried to write the MBR.
> >
> > Fix attempts:
> > I've gone through untold iterations of grub2-install commands, mainly
> > trying different modules and what not.
> > The only clue I've gotten is when running grub2-install with --debug
> which
> > provides:
> >
> > grub2-install: info: /dev/md125 is not present.
> > grub2-install: error: unknown filesystem.
> >
> > However, md125 is the /boot array and it's definitely there so I'm
> thinking
> > this may be a red herring.
> >
> > I'm tempted to just use --force since it seems to be checking unrelated
> > filesystems but was hoping someone with more grub experience would chime
> in.
> >
> > Thoughts?
> >
> > Thanks!
> > -Lee
> > --
> > This message was sent to: Ron Kelley <rkelleyrtp at gmail.com>
> > To unsubscribe, send a blank message to trilug-leave at trilug.org from
> that address.
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>
>