[Engine-devel] [node-devel] Support for stateless nodes

[Doron Fediuck]

On 22/02/12 16:57, Mike Burns wrote:
> There has been a lot of interest in being able to run stateless Nodes
> with ovirt-engine.  ovirt-node has designed a way [1] to achieve this on
> the node side, but we need input from the engine and vdsm teams to see
> if we're missing some requirement or if there needs to be changes on the
> engine/vdsm side to achieve this.
> 
> As it currently stands, every time you reboot an ovirt-node that is
> stateless, it would require manually removing the host in engine, then
> re-registering/approving it again in engine.  
> 
> Any thoughts, concerns, input on how to solve this?
> 
> Thanks
> 
> Mike
> 
> [1] http://ovirt.org/wiki/Node_Stateless
> 

Some points need to be considered;

- Installation issues

* Just stating the obvious, which is users need
to remove-add the host on every reboot. This will
not make this feature a lovable one from user's point of view.

* During initial boot, vdsm-reg configures the networking
and creates a management network bridge. This is a very
delicate process which may fail due to networking issues
such as resolution, routing, etc. So re-doing this on
every boot increases the chances of loosing a node due
to network problems.

* CA pollution; generating a certificate on each reboot
for each node will create a huge number of certificates
in the engine side, which eventually may damage the CA.
(Unsure if there's a limitation to certificates number,
but having hundreds of junk cert's can't be good).

* Today there's a supported flow that for nodes with
password, the user is allowed to use the "add host"
scenario. For stateless, it means re-configuring a password
on every boot...

- Other issues

* Local storage; so far we were able to define a local
storage in ovirt node. Stateless will block this ability.

* Node upgrade; currently it's possible to upgrade a node
from the engine. In stateless it will error, since no where
to d/l the iso file to.

* Collecting information; core dumps and logging may not
be available due to lack of space? Or will it cause kernel
panic if all space is consumed?

-- 

/d

"Hi, my name is Any Key. Please don't hit me!"