On 10/12/14 18:13, Jeff Boyce wrote:
> Greetings -
>
> The short story is that got my new install completed with the
> partitioning I wanted and using software raid, but after a reboot I
> ended up with a grub prompt, and do not appear to have a grub.cfg file.
> So here is a little history of how I got here, because I know in order
> for anyone to help me they would subsequently ask for this information.
> So this post is a little long, but consider it complete.
>
> Brand new Dell system with two 3GB drives in this system with RAID1 LVM
> taking all the space outside the boot partitions. I initially created
> the sda[1,2] and sdb[1,2] partitions via GParted leaving the remaining
> space unpartitioned. A gpt partition table was put on both drives.
> During installation Anaconda recognized everything properly which
> resulted in the following partition summary:
>
> sda1 /boot/efi 500 MB EFI System Partition
> sda2 /boot 500 MB xfs
> vg_jab-hostroot / 8 GB LVM xfs RAID1
> vg_jab-hostvar /var 4 GB LVM xfs RAID1
> vg_jab-hostswap /swap 2 GB LVM swap RAID1
>
> The installer also recognized and listed these unknown partitions that
> were untouched during installation.
> sdb1 vfat 500 MB standard partition
> sdb2 vfat 500 MB standard partition
>
> Installation proceeded successfully, and after the initial reboot of the
> system I used mdadm commands to watch the raid complete building before
> doing anything else (I know, not necessary but I am doing other things
> and had the time to let it complete). I rebooted the system and got a
> terminal prompt as expected (no GUI installed). At this point I needed
> to copy my /boot/efi and /boot partitions from sda[1,2] to sdb[1,2] so
> that the system would boot from either drive, so I issued the following
> sgdisk commands:
>
> root# sgdisk -R /dev/sdb1 /dev/sda1
> root# sgdisk -R /dev/sdb2 /dev/sda2
> root# sgdisk -G /dev/sdb1
> root# sgdisk -G /dev/sdb2
>
> Results of the first command above:
> Found invalid GPT and valid MBR; converting MBR to GPT format.
> Warning the kernel is still using the old partition table. The new
> table will be used at the next reboot. The operation has completed
> successfully.
> The same note (from the Warning on) was repeated for the other three
> commands.
>
> I then installed GRUB2 on /dev/sdb1 using the following command:
> root# grub2-install /dev/sdb1
> Results: Installing for x86_64-efi platform. Installation finished.
> No error reported.
>
The upstream docs (see below) seem to suggest 'grub2-install /dev/sdb'
rather than /dev/sdb1 (i.e, installing to the device rather than a
partition on the device). I don't know if this is the cause of your issue.
> I rebooted the system now, only to be confronted with a GRUB prompt.
> Thinking that this is a good opportunity to for me to learn to rescue a
> system since I am going to need to understand how to recover from a disk
> or raid failure, I started researching and reading. It takes a little
> bit of work to understand what information is valuable when a lot of it
> refers to GRUB (not GRUB2) and doesn't make reference to UEFI booting
> and partitions. I found this Ubuntu wiki as a pretty good source
> https://help.ubuntu.com/community/Grub2/Troubleshooting#Search_.26_Set
>
I found the upstream documentation for grub2 to be useful:
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/ch-Working_with_the_GRUB_2_Boot_Loader.html
Included is a procedure for completely reinstalling grub2 which might
help you recover.
> Below is the current information of my system as seen by grub;
>
> grub# set (the important grub2 variables are:)
> prefix = (hd1, gpt2)/grub2
> root = hd1, gpt2
>
> grub# ls -lha
> Device proc: filesystem type procfs
> Device hd0: no known filesystem detected
> Device hd1: no known filesystem detected
> Partition hd1, gpt3: no known filesystem detected
> Partition hd1, gpt2: filesystem xfs
> Partition hd1, gpt1: filesystem fat
> Device hd2: no known filesystem detected
> Partition hd2, gpt3: no known filesystem detected
> Partition hd2, gpt2: no known filesystem detected
> Partition hd2, gpt1: no known filesystem detected
>
> grub# ls (hd1, gpt2) -l /
> /efi
> /grub
> /grub2
> vmlinuz -3.10.0-123.el7.x86_64
> initramfs-3.10.0-123.el7.x86_64.img
> ... plus some other files
>
> Looking through the directories, I see that there is no grub.cfg file.
> Other than grub not recognizing the filesystem on hd2, the directories
> on hd2, gpt[1,2] seem to be identical to hd1, gpt[1,2] as I would assume
> based on the sgdisk commands I gave to copy them. My initial thinking
> is that I need to re-run grub2-install on hd1 (sda), but I need a
> running system to do that. So following the guidance I had I issued the
> following commands in grub to boot the system.
>
> grub# linux /vmlinuz -3.10.0-123.el7.x86_64 root=/dev/sda2 ro
> grub# initrd /initramfs-3.10.0-123.el7.x86_64.img
> grub# boot
>
> Unfortunately the system hung on booting, with the following information
> in the "journalctl" file:
> # journalctl
> Not switching root: /sysroot does not seem to be an OS tree.
> /etc/os-release is missing.
> Initrd-switch-root.service: main process exited, code=exited,
> status=1/FAILURE
> Failed to start Switch Root.
> . . . . .
> Triggering OnFailure= dependencies of initrd-switch-root.service.
> Starting Emergency Shell. . .
> Failed to issue method call: Invalid argument
>
> Now I am not sure that I want to get misdirected to what the problem is
> with this boot, if I can boot from a CD in linux rescue mode and do the
> grub install, then be back to a booting system. So lets ignore the boot
> error if we can. So I boot from a CD in rescue mode, and it is only
> able to automatically mount sd3 under /mnt/sysimage (the LVM RAID1
> containing mounts for / and /var). I am able to manually mount sda1 and
> sda2, but am not sure at what level in the filesystem to mount them
> (i.e., at /mnt/sda1 or at mnt/sysimage/sda1) in order to properly run
> grub2-install.
>
> So that is where I am at now. I would like to know how to repair the
> system, rather than starting over on a new install. Can someone
> enlighten me on what I need to do from here. Also if someone can
> speculate on why my grub.cfg is missing in the first place I would be
> interested.
>
> Also, please cc me directly on any responses, as I am only subscribed to
> the daily digest. Thanks.
>
> Jeff Boyce
> Meridian Environmental
> www.meridianenv.com
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