Re: CentOS 7: restore fails

Nikolaos Milas <[email protected]>
Newsgroups gmane.linux.mondo.devel
Organization National Observatory of Athens
Message-ID <[email protected]>
On 24/1/2017 7:47 μμ, Bruno Cornec wrote:

> Humm seems you have a mismatch between the IDs referenced in your grub conf and what exists on your system.
> Have a look athttp://mondorescue.org/docs/p2v.pdf
> Old now, put still pretty acurate wrt what you have to do.

Hi Bruno,

I'm still struggling with this.

My recent experiences:

A recent restore still failed in the same way.

I tried to repair using: 
https://sourceforge.net/p/boot-repair-cd/home/Home/ but it didn't manage 
to solve the problem.

More interesting was the effort with the supergrub2 disk: 
http://www.supergrubdisk.org/super-grub2-disk/

This managed to identify the available "boot methods" and allowed me to 
boot correctly! See attached screenshots. (00,01,02).

Once I logged in, I checked /etc/fstab and /boot/grub2/grub.cfg but I 
didn't see any obvious problem. (I attach them here for your reference.)

However, I also followed these directions: 
https://www.techbrown.com/reinstall-grub2-boot-loader-centos-7-rhel-7.shtml 
to rebuild grub2.conf. The commands were completed successfully.

Unfortunately, the OS still won't boot: see image -04.

I retried to boot using the supergrub2 disk; this time the boot method 
probe produced the (slightly different) list you see in image -05. I 
still can login when booting from the supergrub2 disk. Otherwise (i.e. 
directly) the box won't boot successfully.

As I know little about grub2 (and low-level linux) to troubleshoot the 
issue, can you please help identify and correct the problem?

Which is the reported device (on image -04) that remains unrecognized? I 
looked into /boot/grub/grub2.cfg but I didn't see any such UUID there.

Note: I never have such issues when restoring CentOS 5 or CentOS 6 
backups (even on dissimilar virtual hardware), so it seems the problem 
lies with grub2.

Many thanks,
Nick

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supergrub2-scratchvm-20170503-00.png (image/png, 17.9 KB) - not displayed
supergrub2-scratchvm-20170503-01.png (image/png, 11.4 KB) - not displayed
supergrub2-scratchvm-20170503-02.png (image/png, 25.5 KB) - not displayed
fstab (text/plain, 582 B)
#
# /etc/fstab
# Created by anaconda on Thu Dec  8 13:40:06 2016
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root /                       xfs     defaults        0 0
UUID=297e2939-d6f5-431a-9813-9848368ee306 /boot                   xfs     defaults        0 0
/dev/mapper/centos-swap swap                    swap    defaults        0 0
10.201.40.34:/data/col1/noc-bkups-1   /mnt/dd2500-1   nfs auto,noatime,nolock,bg,nfsvers=3,intr,tcp,actimeo=1800 0 0
grub.cfg (text/plain, 4.8 KB)
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub2-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
set pager=1

if [ -s $prefix/grubenv ]; then
  load_env
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="${saved_entry}"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

terminal_output console
if [ x$feature_timeout_style = xy ] ; then
  set timeout_style=menu
  set timeout=5
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
  set timeout=5
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/00_tuned ###
set tuned_params=""
### END /etc/grub.d/00_tuned ###

### BEGIN /etc/grub.d/01_users ###
if [ -f ${prefix}/user.cfg ]; then
  source ${prefix}/user.cfg
  if [ -n ${GRUB2_PASSWORD} ]; then
    set superusers="root"
    export superusers
    password_pbkdf2 root ${GRUB2_PASSWORD}
  fi
fi
### END /etc/grub.d/01_users ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'CentOS Linux (3.10.0-514.10.2.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-327.el7.x86_64-advanced-fcee6215-e97a-4a4f-9473-5115f8559683' {
	load_video
	set gfxpayload=keep
	insmod gzio
	insmod part_msdos
	insmod xfs
	set root='hd0,msdos1'
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  297e2939-d6f5-431a-9813-9848368ee306
	else
	  search --no-floppy --fs-uuid --set=root 297e2939-d6f5-431a-9813-9848368ee306
	fi
	linux16 /vmlinuz-3.10.0-514.10.2.el7.x86_64 root=/dev/mapper/centos-root ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=en_US.UTF-8
	initrd16 /initramfs-3.10.0-514.10.2.el7.x86_64.img
}
menuentry 'CentOS Linux (3.10.0-514.6.1.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-327.el7.x86_64-advanced-fcee6215-e97a-4a4f-9473-5115f8559683' {
	load_video
	set gfxpayload=keep
	insmod gzio
	insmod part_msdos
	insmod xfs
	set root='hd0,msdos1'
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  297e2939-d6f5-431a-9813-9848368ee306
	else
	  search --no-floppy --fs-uuid --set=root 297e2939-d6f5-431a-9813-9848368ee306
	fi
	linux16 /vmlinuz-3.10.0-514.6.1.el7.x86_64 root=/dev/mapper/centos-root ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet LANG=en_US.UTF-8
	initrd16 /initramfs-3.10.0-514.6.1.el7.x86_64.img
}
menuentry 'CentOS Linux (0-rescue-70755ad829254eb99c7de84a01a3ce0b) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-0-rescue-70755ad829254eb99c7de84a01a3ce0b-advanced-fcee6215-e97a-4a4f-9473-5115f8559683' {
	load_video
	insmod gzio
	insmod part_msdos
	insmod xfs
	set root='hd0,msdos1'
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  297e2939-d6f5-431a-9813-9848368ee306
	else
	  search --no-floppy --fs-uuid --set=root 297e2939-d6f5-431a-9813-9848368ee306
	fi
	linux16 /vmlinuz-0-rescue-70755ad829254eb99c7de84a01a3ce0b root=/dev/mapper/centos-root ro crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet
	initrd16 /initramfs-0-rescue-70755ad829254eb99c7de84a01a3ce0b.img
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_ppc_terminfo ###
### END /etc/grub.d/20_ppc_terminfo ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  ${config_directory}/custom.cfg ]; then
  source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
supergrub2-scratchvm-20170503-04.png (image/png, 7.1 KB) - not displayed
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