Source:Troubleshooting Disaster Recovery

From SEPsesam

Disaster recovery on Linux

Problem with a ReaR backup execution on SEP sesam Client


  • ReaR backups on the SEP sesam Client are experiencing issues, but path backups are functioning correctly. The backup log may contain errors such as sbc_vadp requires additional libraries (fatal error).
  • Example:
    opt/sesam/bin/sesam/sbc_vadp requires additional libraries (fatal error) => not found


  • This issue is caused by the sbc_vadp binary, which was included in the Service Pack 1 update, but is not required on the Client.


Delete the sbc_vadp binary. You can use the following command:

rm /opt/sesam/bin/sesam/sbc_vadp

The workflow mkrescue is not supported in the ReaR system


  • The workflow mkrescue is not supported in the ReaR rescue/recovery system.


  • Delete the file /etc/rear-release.

ReaR image hangs during bootup


  • The system hangs during bootup like shown in the following image:


  • Boot the system with the ACPI=OFF option (this option can be specified on the command line in the boot menu prompt, after the options BACKUP=SESAM OUTPUT=ISO).

The recovered system does not boot

Problem 1

  • The system does not boot because /root/dev/console cannot be found.

Possible causes

  • 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/:
  1. Boot from the SEP sesam LIVE CD.
  2. Mount the ROOT partition of the restored system.
  3. Manually create the /dev/ directory.
  4. Manually create the /dev/console entry with:
mknod /path/to/target/mount//dev/console c 0 0

Problem 2

  • The system does not boot because of missing

Possible cause

  • This is most likely caused by SELinux which is activated by default.


  • Especially on RHEL6 or CentOS6 systems, follow these steps after rebooting from the ReaR recovery:
    1. Press a key when prompted by the boot loader (GRUB):
    2. Select the appropriate boot loader entry:
    3. Press e to modify the commands for the selected entry:
    4. Add selinux=0 to the commands:
    5. Press Enter to confirm the changes and b to boot up the machine with SELinux disabled.
    6. When having access to the system, change the option SELinux of /etc/selinux/config to the following:
    7. SELINUX=permissive

    Afterwards, reboot the system and feel free to set the SELinux value back to enforcing if needed.

No bootable operating system can be found


  • The system is not able to find a bootable OS instance after the restore.

Possible causes

  • 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

Possible causes

  • Check the file /boot/grub/ 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:
hd(0) /dev/disk/by-id/ata-SAMSUNG_SP2504C_S09QJ1GLA14263-part1


  • 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/'
/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/
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.


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.

Possible causes

  • 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

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

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).

Possible causes

  • 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.

Possible causes

  • 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.

Possible causes

  • 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.

Client does not start on the RHEL6/Debian9 recovery image


  • The SEP sesam Client does not start automatically on RHEL6 and Debian9-based recovery images.


  • The file /etc/init.d/functions is missing within the recovery image.


  • The client can be started manually via:
/opt/sesam/bin/sesam/sm_main start

RHEL7-related issues

RHEL7 backup fails with an error

Error 1

  • The RHEL backup fails with the following error:
ERROR: The LSB package is not installed.


  • Install the lsb package as follows:
yum install redhat-lsb-core mkisofs syslinux

Error 2

  • The RHEL backup fails with:
ERROR: Cannot find required programs: mingetty

For more details, see Rear dependencies on RHEL7.


To solve this problem, proceed as follows:

  1. Edit
  2.  /var/opt/sesam/var/lib/rear/usr/share/rear/conf/default.conf

    and from the line:

    # required programs. Same as above, but if they are missing, we abort.

    remove the line:

  3. Run the backup again.

ReaR error occurred during grub2-mkimage of bootx64.efi

In order to be able to create an UEFI/EFI bootable ISO image, the additional tool ebiso has to be installed on the client system as described in the section Installing ebiso for creating UEFI aware ISO images.


  • The ReaR error occurrs during grub2-mkimage of bootx64.efi.


  • To solve the problem, install the grub2-efi-x64-modules package.

SLES-related issues

SM_SSH does not work on SLES11 recovery image


  • In this case, execute
mount -t tmpfs none /dev/shm/ -o rw,nosuid,nodev,noexec
before starting the recovery process.

Client is unreachable after booting the rescue image


  • After booting the rescue image the client is not reachable.


  • Start the client manually using the following command on the rescue command line:
sh /etc/scripts/system-setup.d/

EFI bootable image cannot be created on SLES11


  • EFI bootable image of GRUB2 cannot be created on SLES11.


  • SEP sesam v. Grolar is the last version that supports SLES11 with UEFI.


  • To continue using SLES with UEFI, you should not upgrade to a later version of SEP sesam.

Installing ebiso for creating UEFI aware ISO images

In order to be able to create an UEFI/EFI bootable ISO image the, the additional tool ebiso has to be installed on the client system. This package is not part of a regular SLES12/SLES15 installation and can be downloaded at the following URL:


For other Linux distributions contact SEP support at for assistance.

Install ebiso as follows:

rpm -i ebiso-<version>.rpm

Note that in ReaR v. < 1.19, the generated ISO image mount migt be too small for storing all needed information and need to be adjusted.

In this case, under

/var/opt/sesam/var/lib/rear/usr/share/rear/lib/ (line 64)


(shim.efi|elilo.efi) size=128000 ;;


(shim.efi|elilo.efi) size=228000 ;;
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