topic Re: Linux - recovery from mkbootdisk in Operating System - Linux

Linux - recovery from mkbootdisk

Duffs — Mon, 18 Oct 2010 09:58:37 GMT

Hi,

I am in the process of putting togeather a DR plan/procedure for a redhat (AS5) production box. I currently have got all FS's being backed up using HP Data Protector. In addition to this I was planning on making a boot disk of the MBR in the event of disk corruption and saving it to CD/USB. I am not familiar with this procedure so need some advise on how/what will actually recover in the event of disk failure?

I plan on running (in S-user mode):
# mkbootdisk --iso --device boot_cd.img ùname -r`

to recover:
- interrupt bootup & run 'linux rescue '
- insert CD/USB

My questions are:
1)Is this procedure correct? ....and if so....
2)Is this procedure (accompanied with DP restore) enough to recover an entire system?

Regards,
Duffs

Re: Linux - recovery from mkbootdisk

Matti_Kurkela — Mon, 18 Oct 2010 16:46:20 GMT

First I must ask you: why are you *asking* this when you should be *testing* your procedure? Even if you're sure the procedure works, testing would give you a chance to familiarize yourself with the procedure. To me, that alone would be reason enough to test it.

1.) On PC hardware, you must insert the boot media while the system is still running BIOS self-tests. Once the system loads the bootloader from hard disk, switching to CD-ROM or network boot will no longer be possible. (The BIOS extensions that handle CD-ROM or network boot will be switched off at that point.)

So the correct order of steps is: *first* insert CD/USB, *then* interrupt bootup and specify boot options if necessary.

2.) I haven't tested mkbootdisk, so I'm not sure whether your command syntax and boot options are correct or not. But a quick Googling seems to indicate a boot CD created with mkbootdisk would only help if you have problems with your kernel and/or bootloader: if your root filesystem has been corrupted, that is not enough to recover.

Mondo Rescue is the closest equivalent of HP-UX Ignite for Linux environments:
http://www.mondorescue.org/

MK

Re: Linux - recovery from mkbootdisk

Zinky — Wed, 20 Oct 2010 14:13:30 GMT

Duffs,

You Sir are on the right track. But you need to define what your DR is for, to wit:

1) Is it for an expected/accidental catastrophe to your Server's OS?
2) Is it for a true Full DR scenario - wherein you will need to re-establish your server environment at a possibly dissimilar HW (server, HBA, storage) environment?

For 1) - there are many ways one can mitigate such issues. Here are my solutions:
a) Have an alternate / easily refreshed alternate OS environment. I can shoot you a recipe.
b) Keep your OS environment on SAN disks which will give you the ability to snapshot/clone your OS disk for easy fallback

For 2) - MondoRescue is the BEST solution hands down. It offers the admin an easy way to restore the OS and the environment to dissimilar HW. You'll need to be intimate with Linux though but it is the closest thing to HP-UX Ignite as Matti pointed out.

Of course back to your original question - Yes I believe that is how you would normally make use of your mkbootdisk boot environment to get to the oft-tedious "Linux Rescue" environment.

Of course there are ither specialized BootRescuers out there like SystemRescueCD or even Knoppix -- which you could develop a quick liking but MondoRescue *is* the best IMHO.

FWIW, cheers!

Re: Linux - recovery from mkbootdisk

Duffs — Wed, 20 Oct 2010 14:30:07 GMT

MK, Firstly to answer your qu; ain't got time to mess about testing especially not on a prod box - not a good idea if things go pair-shaped. But thanks for the tipps anyhow.

Alzhy, thanks for the advice & as MK mentioned I will look into Mondo Rescue.

R,
D.

Re: Linux - recovery from mkbootdisk

Duffs — Wed, 20 Oct 2010 14:31:39 GMT

Conclusiion is Mondo Rescue is best option for Linux DR.