VirtualTam's bookmarks

1. Centos/RHEL 7 - Fix LVM boot issues after migration from ESXi to VirtualBox 2018-04-20

   tags: boot, bootloader/grub, filesystem, filesystem/lvm, fstab, linux, linux/centos, linux/kernel, linux/red-hat

   [ permalink ]

   Here are the steps I used to migrate a CentOS 7 VM from (presumably?) an ESXi server, to a local VirtualBox environment.

   The LVM volumes were not detected at boot, and after the boot timeout, the OS fell back to the Dracut emergency shell.

   • get a CentOS minimal installation CD
   • check the VM's resources and peripherals:
     • ensure there are no floppy drives (!)
     • setup CPU and RAM resources
     • check virtual drives
     • add an SCSI optical drive if needed
   • optional: convert the virtual drive images from VMDK to VDI
   • mount the CentOS installation disc
   • boot on the installation disc:
     • select "Troubleshooting", then "Rescue"
     • let the rescue utility detect filesystems and mountpoints
   • $ chroot to the detected environment
   • backup files:
     • /etc/fstab
     • /boot/grub/grub.cfg
   • under /boot, backup the initrd and initramfs for the current configuration (these will be overwritten)
   • compare the current /etc/fstab with the output of $ lsblk and $ blkid
   • if needed, manually edit /etc/fstab to use the appropriate block device UUIDs, identifiers and mountpoints
   • regenerate GRUB configuration:
     • $ grub2-mkconfig -o /boot/grub2/grub.cfg
   • if needed, reinstall GRUB:
     • $ grub-install /dev/sda
   • rebuild initrd:
     • $ mkinitrd --force /boot/<initrd_image> <kernel_version>
   • rebuild initramfs:
     • $ dracut --force <kernel_version>
   • exit the chroot
   • unmount the installation disc
   • reboot
   • optional but highly recommended: cross your fingers
   • ...
   • profit!