Starting a FAI installation using kexec

[Torsten Schlabach]

Hi Jean!

> i think the goal here is to take any machine from a provider that you
> do not control via dhcp or pxe and use fai anyway to reinstall it
> from scratch.

I couldn't have explained it better.

 > If you knwo how i am interested :)

Well, as I already mentioned, some ideas (which have worked in the past) 
can be found here:

http://faiwiki.informatik.uni-koeln.de/index.php/Using_FAI_to_install_a_root_Server

Just that method described there isn't as elegant as it would be using 
kexec (or possibly root_pivot, I am currently looking into that 
alternative) because you always have only one shot. I.e. you change the 
boxes' boot loader config to boot the FAI install kernel with NFS root. 
Either that succeeds and you're find or you have made any mistake which 
prevents it from working (typo in IP address, wrong root partition in 
grub config, install kernel does not recognize the NIC, you name it) and 
you'll be in for a complete re-staging of the server to try again. Read: 
1-2 hours waiting.

Even a bit worse, actually ...

We do have a DC provider who does not have an automated system to 
re-stage the server with their default image to get ready for the next 
attempt. We do have an automated reset though.

Of course, all of this here would be definitely a bit easier if you had 
a remote KVM console for the server. But then again, this is a feature 
which is prohibitively priced in many DCs. And you'd need it only once 
for the installation.

My point is:

Is there any difference between loading an install kernel with a given 
parameter line via PXE or doing the same off kexcec. In theory there 
shouldn't be. In practice, there seems to be ...

Regards,
Torsten


Jean Spirat schrieb:
> 
>> I might not fully understand your case, but on an already 
>> basic-installed system, I'd simply run fai softupdate.
>> 
>> Wasn't kexec some system for changing the running kernel without
>> reboot?
>> 
>> Henning
>> 
>> 
> i think the goal here is to take any machine from a provider that you
> do not control via dhcp or pxe and use fai anyway to reinstall it
> from scratch.
> 
> If you knwo how i am interested :)
> 
> 
> regards, Jean.