Re: How to make a rescue disk ?

[Alvin Oga <aoga@mail.Linux-Consulting.com>]

hi ya bruno

On Sun, 23 Oct 2005, Bruno Costacurta wrote:

> I'm looking for procedure / howto about creating rescue CD disk.

proceedure .. "think" :-) ..
	- find out what hardware chipset is in your pc
	- find out what kernel you're using
	- save the kernel and /lib/modules/<kernel>
	- save your partition info
	- save your list of apps installed
	- save your list of config files installed
	- add dressing so that you can do something
	( bash, libc, networking, fs-check apps, ... )

	- how much time will have you "rescue" the dead box ?

	  5min .. 5hrs .. 5 days .. would dictate how you implement
	  your rescue cd

	- depending on what you want to rescue .. existing
	"rescue" cd's will not have your config files and setup

	- or do you want rescue to save a corrupt fs vs
	a backup of your /home and config changes which
	is not the same as rescue

	- booting the pc is not the same as rescue either

how complicated do you want to get ...
	- why start with the hardest way to rescue a system ?

0)  dd if=/boot/vmlinuz of=/dev/fd0
	- as long as your kernel is 1.2MB and you have the network
	modules you can always boot can get online 

1)  do a fancier boot floppy with ( lilo or grub or syslinux ) menu 
	- lots of howto's

2)  stick a 2nd disk into the same system ... and mirror your boot info
    and may as well copy your /home/bruno directories too

3)  use raid ... in case hda dies ... your properly configured raid
    will boot off hdc instead

4)  make a bootable usb-stick ( more space than a floppy )
	this is the simplest "1 minute change" but assumes your
	system supports usb-hdd-boot and your system has the usb 
	driver modules

	lilo -C /etc/lilo.hda.conf	
		--> change to boot=/dev/hda to boot=/dev/sda

	more tweeking (2 min) of menu.lst for "grub-install /dev/sda"

4)  setup (pxe) network boot ... so that you always boot off the network
    as long as the pxe server is running 

5)  use an existing "standalone" cdrom
	- you're assuming the kernel on the cdrom supports your hw
	or else it's worthless for rescuing your hardware

6) make your own standalone cdrom
	- little more work ... but more fun

	- rescue cd  needs initrd.gz  and rootfs ....
	and you'd need to make an iso of the whole thing

	hacking a existing knoppix is easy but is too big
	of a rescue disk

7) test and retest from different failures

8) endless list with more variances and differences of how to boot it

c ya
alvin