Ramdisk only Rescue System - a rescue system completely held in memory

The Ramdisk only Rescue System allows you to access all drives without any limitation once the system is bootet. It will neither mount the CD nor any harddisk it was booted from.
Click ->here<- for downloads.

Why another rescue system? Aren't there enough?

The system was basically develloped for my Rootserver installation article in the Linux-Magazin 10/2004. If you want to install a new distribution on a remote system and have no separate rescue system, you're in trouble: How do you want to get rid off the old system without mixing the files with the new one?

Hey, there's no documentation in the tar archive!

The usage is very simple: Copy the Kernel and the initial ramdisk of this rescue system to the /boot directory of your harddisk, then add a new section to your favorite bootloader (I recommend Grub).

The rescue system will start a SSH daemon to allow remote root logins. Have a look at the Grub configuration example rescue-menu.lst, it shows you how to pass the network settings to the rescue system. Currently there is no DHCP, sorry.

With Grub and the savedefault-Patch you can try out the rescue system without any risk, in worst case you have to reboot the system e.g. by a web frondend (ask your hoster how to do this, in some cases it's not for free) and your old system will boot again.

During the boot process, the rescue system will configure your first network device, generate some fresh SSH host keys and start sshd for your logins. There is only the root user and his password is "RoRSresc". Have in mind that this means everyone could easily log into your server while you're running the rescue system.

RAM is not static, so I have to install it on my Rootserver disk, and this means I cannot repartition or erase the partitions/harddisks. Q.E.D

Once the rescue system is running, you can do whatever you like with your drives -- formatting, repartitioning, throwing the harddisk away. The clue is: the 4 MB initial ramdisk is loaded completely into memory, right after the kernel -- and that's all the rescue system needs for breathing. It will take additional 16 MB for a ramdisk so you can store some files, all together you need about 32 MB minimum to run this system.

Caution! In Version 0.1 you only have a german keyboard layout and there is absolutely nothing you can do about this!

If you just delete your harddisks or fill it with zeros, the rescue system won't even notice. As long the rescue system is running in memory, you have access via a serial console, SSH and four terminal consoles.

OK, I formatted the disk and installed my new distribution. How do I remove the rescue system?

If you have formatted the partition or whole harddisk, the rescue system is already gone. You just need to rewrite the bootloader. If you did not overwrite your /boot partition, just delete the rescue kernel and its initial ramdisk, then rewrite the bootloader -- that's all.

But if you have just 5 MB left on your disk: What about keeping the rescue system on the disk? Perhaps, one day, you could need one and then you don't need to bother finding your favourite rescue CD. Just choose the rescue system from the boot menu.

Sincerely,
Mirko <cooper@linvdr.org>