Last update: June 30, 2008
You need configure the system restored to dissimilar hardware before you can boot it
This article applies to:
Introduction
You can use Acronis True Image to back up and restore a Linux machine.
If you back up a Linux machine and then restore the backup to the same machine or to a machine with similar hardware, you should be able to boot the system immediately after the restore.
If you restore the backup to a machine with dissimilar hardware, you will need to configure the restored system before you can boot it.
(!) The solution provided in this article is realized through the means of Linux. At the moment, there is no Acronis software that can perform this task.
Solution
Brief description of Linux boot process
- The process starts with the boot loader. The Linux boot loader, which in most cases is GRUB or LILO, reads its configuration and unpacks the kernel and Ramdisk into memory. After this it passes the control to the kernel;
- After Ramdisk (RAM file system) is unpacked, a certain amount of memory is used by the kernel as a secondary storage device. Then the system loads modules and executes the scripts necessary for hardware usage. After this the physical devices are mounted and the memory used by Ramdisk gets free.
Device mounting during the boot procedure is processed according to rules specified in the /etc/fstab file. This file contains the list of devices to be mounted, their mount points, options to be passed to mount syscall and some service information.
Necessary conditions to boot Linux system
To boot the system it is necessary to get the /boot and / directories mounted (they can reside on different partitions). Here is the list of required conditions:
- The boot loader is configured properly (e.g. it can access and unpack the kernel and Ramdisk);
- Driver modules necessary to detect and mount the hard disk controller on which the root file system is located are either in the kernel or in Ramdisk;
- The /etc/fstab file contains the correct description of devices and their mount points.
Configuring the Linux system restored to dissimilar hardware
- Rebuild Ramdisk with all the necessary modules included. To do this you can use Live Media of your Linux distribution based on the kernel similar to the restored one. Here is the rough list of actions:
- Boot from Live Media, check if all the necessary mass-storage devices are detected. Then take a look at the output of lsmod to find what modules must be included;
- Mount the /boot partition;
- Mount the /proc and /sys file systems;
- chroot into the mounted directory and build new Ramdisk (e.g., with the mkinitrd command) including all necessary modules.
- Edit /etc/fstab if the drive or partition devices were changed (e.g., you restored file systems from LVM volumes to physical partitions);
- Edit boot loader configuration:
- Check that root= option refers to the proper root partition device
- Pass the correct initrd option
- Reactivate boot loader. See Reactivating Linux Loaders (GRUB, LILO).
More information
For detailed instructions please consult with the development team of your Linux distributive.
See also Restoring LVM Volumes with Acronis True Image.
Operating Systems:
Linux Distribution
