[baylisa] Re: wtf: hostid gives '0' as a hostid

Mon Feb 18 20:21:02 PST 2008

On Feb 18, 2008, at 7:29 PM, cerise at armory.com wrote:

> On Mon, Feb 18, 2008 at 07:07:39PM -0800, Jeff Younker wrote:
>> 1) IP addresses change.
>
> Irrelevant, so long as /etc/hostid changes with it.  It marks a
> unique host.

That assumes that your deployment system works with hosts that have an
OS installed.  A deployment system that I helped to build had to  
identify
systems before this was available.

When unknown systems were placed onto the network they were
given a minimal OS install by DHCP and placed into a 'limbo' network
consisting of unallocated machines.

This minimal OS install contacted a central server (identified by a  
bootp
parameter) and fed over its identifying information.  This included a  
serial
number (dell hardware) and MAC address along with as much various data
about its hardware configuration.

The new information had two effects. Either it created a new row in a
hosts database, or it updated an existing record with the mac address.

If the information in the database was sufficient to assign the host  
to a
cluster then a new DHCP configuration would be generated and DNS would
be updated if needed.  Finally the minimal OS would detect the change in
assignment by querying the config server, and then reboot, this time  
coming
up with a full OS install and its new identity.

  The upshot of this process is that it was never necessary to enter any
networking information about a host.  Networking ranges were assigned
to clusters, and the install system determined the mac addresses on  
its own.

The whole thing is possible because the system can locate a hardware
identifying key.

-jeff