Four rescue systems compared

Emergency Response

Rescatux for Complex Tasks

The final rescue system to discuss is Rescatux (Figure 4) [7], which differs from the others by catering to beginners, unlike Grml and SystemRescueCd. Therefore, Rescatux is not meant to be a comprehensive recovery tool for server administrators facing an emergency. Instead, Rescatux aims to make it as easy as possible for users to get their broken Linux desktop installations up and running again.

Figure 4: Rescatux is the surprise in the test: Rescapp is oriented toward inexperienced users and performs many tasks with just a few clicks.

Whereas Knoppix essentially provides all the tools you need to resuscitate a broken desktop Linux, albeit with a bit of sysadmin experience to use the tools appropriately, Rescatux boots into Rescapp, a GUI that displays various buttons for diagnosing and fixing common system problems. For example, you can rewrite GRUB to the bootloader (Figure 5) or enforce a filesystem check.

Figure 5: Rescapp formulates clear questions for users who are not professional administrators and sets up GRUB based on the answers.

The list of functions that Rescatux combines in Rescapp is impressive. Above all, however, it is a tool for repairing broken GRUB installations. The development of Rescapp was initiated by the change from GRUB 1, which let you switch to a command line if the originally installed GRUB was faulty, to GRUB 2, which does not: You must have a running Linux system to repair a broken GRUB 2. With Rescapp, you retain the capability to restore GRUB.

After Rescatux boots, Rescapp automatically opens in the LXDE desktop; clicking the Grub (+) line unfolds the restore menu for the Linux bootloader.

Clicking Restore Grub takes the user directly to a wizard: In the first step, the wizard asks which operating system you want to display as an entry in the GRUB configuration. The tool is based on Debian and uses the os-prober application, which is part of the Debian installer, in the background.

In the next step of the wizard, the user specifies the disk on which the bootloader should be installed before specifying the order of the disks in the final step (a new device.map is created from this information in the background). A final click sets the Rescapp mechanism in motion. GRUB should then execute on the system as usual.

Linux, but Not Just

In addition to handling all sorts of GRUB commands, current versions of Rescatux can force a filesystem check (including ext4 and XFS), change the root password, and regenerate an accidentally deleted sudoers file. Various tools for experts include GParted for disk partitioning or extundelete at the command line for recovering accidentally deleted files.

Some important commands cater to Windows systems. For example, anyone who wipes out the Windows MBR while setting up a dual-boot setup can restore it using the Rescatux CD. Rescapp also changes the administrator password on Windows systems, and it is even possible to add a Windows user to the administrator role. If you accidentally lock your Windows account, you can solve that problem in the Windows section. The most current Windows functions are still listed as beta in the tool's documentation – which means the developers cannot guarantee that they will work properly. Although the Rescatux approach might seem unusual at first glance, on closer inspection, the rescue system demonstrated its usefulness.

Rescatux is not suitable for administrators working on servers in the data center. Grml, Knoppix, or SystemRescueCd are best used by this group. Rescatux is more oriented toward inexperienced users who just want to use their broken Linux installations again.

Conclusions

A review of current rescue systems reveals great diversity. Grml clearly positions itself in the server section; Rescatux, on the other hand, is ideal for desktop system users. SystemRescueCd holds the middle ground, offering graphics, but it also works satisfactorily on servers. Knoppix is a special, but useful, case if the 4.7GB download doesn't pose a problem, The comprehensive desktop system has all the server recovery trimmings you could imagine.

The Author

Martin Gerhard Loschwitz works as a cloud architect at SysEleven GmbH in Berlin, Germany. He focuses on distributed storage, software-defined networking, and OpenStack. He enjoys bowling in his spare time.

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