Disaster Recovery Troubleshooting
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- 1 Disaster recovery on Linux
- 1.1 The recovered system does not boot
- 1.2 No bootable operating system can be found
- 1.3 The device does not have a corresponding BIOS drive
- 1.4 No corresponding BIOS drive for /dev/cciss/c0d0p2
- 1.5 fsck.ext3: File system has unsupported features
- 1.6 Incorrect inode size (256)
- 1.7 Missing root file system
- 1.8 Missing network cards
- 2 See also
Disaster recovery on Linux
The recovered system does not boot
- The system does not boot because /root/dev/console cannot be found.
- Certain distributions rely on the existence of the directory /dev/ while booting
- Certain static devices must exist before the udev daemon creates them.
- Include the /dev/ file system in your backup.
- If the restore cannot restore /dev/:
- Boot from the SEP sesam LIVE CD
- Mount the ROOT partition of the restored system
- Manually create the /dev/ directory
- Manually create the /dev/console entry with:
mknod /path/to/target/mount//dev/console c 0 0
No bootable operating system can be found
- The system is not able to find a bootable OS instance after the restore.
- There may have been problems during the installation of the GRUB boot loader.
- The restore protocol includes a statement whether or not the installation of the boot loader was successful:
2009-12-14 14:48:27: sbc-3500: Info: Reinstall boot manager [/sesam/bin/sesam//sbc_grub_auto /mnt/disk/ AUTO]
- It is also possible to boot the system again from the live-CD, mount the target partitions and use grub-install to install the boot loader correctly.
The device does not have a corresponding BIOS drive
- During the restore, the following error occurs:
/dev/sda1 does not have any corresponding BIOS drive
- Check the file /boot/grub/device.map on the target system. If there are entries referring to the disk through /dev/by-disk/... as shown in the example below, the entry is most likely the reference to the hard disk partition of the broken system. GRUB will not find the proper device:
- Reboot from the live-CD
- Mount the root and boot partitions to /mnt/disk (and /mnt/disk/boot, if necessary)
- Restart grub-install with the following options:
grub-install --root-directory=/mnt/disk --recheck hd0
grub-probe: error: Cannot open `/boot/grub/device.map' /usr/sbin/grub-install: line 374: [: =: unary operator expected Installation finished. No error reported. This is the contents of the device map /mnt/disk/boot/grub/device.map. Check if this is correct or not. If any of the lines is incorrect, fix it and re-run the script `grub-install'. (hd0) /dev/hda (hd1) /dev/hdb
You can ignore the error line 374: [: =: unary operator expected.
More important is the result Installation finished. No error reported.
No corresponding BIOS drive for /dev/cciss/c0d0p2
- You receive the message: /dev/cciss/c0d0p2 does not have any corresponding BIOS drive in restore log.
- Please see: Novell support
fsck.ext3: File system has unsupported features
- During a restore of a system with kernel version 2.4 the system may not boot because the Live-CD creates a file system with features which are not supported by kernel 2.4.
- Most likely the file system options resize_inode,dir_index,large_file,ext_attr are causing the problem and making the system unbootable.
- Reboot from the Live-CD image, which includes the tool debugfs.
- Show the file system features with debugfs:
root@recover#: debugfs -w /dev/sda2 debugfs 1.41.1 (01-Sep-2008) debugfs: features Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file quit
Replace /dev/sda2 with the corresponding partition names on your system.
- To remove file system features:
root@recover#: debugfs -w /dev/sda2 debugfs: features -resize_inode -ext_attr -dir_index -large_file -needs_recovery -sparse_super Filesystem features: has_journal filetype quit
After removing the options, the system should boot correctly.
Incorrect inode size (256)
- After a successful restore the boot process stops with incorrect inode size (256).
- Older kernel versions (2.4) may use a different inode size than the one the file system's created through the Live-CD (which includes kernel 2.6). For example, this happens during the restore of SLES8 based systems which use an inode size of 128k.
- This can only be solved by formatting the devices manually from the Live-CD, using the proper mkfs options:
mkfs.ext3 -I 128 /dev/sda1
After this step, remount the partition to /mnt/disk and repeat the restore operations. Changing the inode size is only possible by reformatting the devices.
Missing root file system
- The restored system can't find a root file system and fails during resume.
- The /etc/fstab file was configured with the root file system as UUID.
- Specify the root file system device name in conventional device names if you are using a different physical disk. After booting, use YAST to reconfigure your boot loader or edit your /boot/grub/menu.lst manually:
Missing network cards
- The restored system does not find any network cards.
- If the restore was done to dissimilar hardware, SLES-based distributions may not configure the network devices correctly. SLES-based systems save their network configuration by using the system's MAC address. Most likely the system will not use eht0 as a device name, but eth1, as it has another MAC address.
- Use YaST and reconfigure your network interfaces.