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On Tue, Apr 8, 2014 at 3:04 AM, Vladimir Kozhukalov <
vkozhukalov at mirantis.com> wrote:

> Guys, thank you very much for your comments,
>
> I thought a lot about why we need to be so limited in IPA use cases. Now
> it much clearer for me. Indeed, having some kind of agent running inside
> host OS is not what many people want to see. And now I'd rather agree with
> that.
>
> But there are still some questions which are difficult to answer for me.
> 0) There are a plenty of old hardware which does not have IPMI/ILO at all.
> How Ironic is supposed to power them off and on? Ssh? But Ironic is not
> supposed to interact with host OS.
>

We can't manage everything... if there's no out-of-band power control,
ironic control the power.


>  1) We agreed that Ironic is that place where we can store hardware info
> ('extra' field in node model). But many modern hardware configurations
> support hot pluggable hard drives, CPUs, and even memory. How Ironic will
> know that hardware configuration is changed? Does it need to know about
> hardware changes at all? Is it supposed that some monitoring agent (NOT
> ironic agent) will be used for that?
>

while an instance is provisioned, ironic does not need to be made aware of
hardware changes.

It has not been written, but it would be fine for Ironic to re-inventory a
server any time it is deleted and before returning it to the pool. I think
it's unnecessary, but it could be possible, with a config option.


> But if we already have discovering extension in Ironic agent, then it
> sounds rational to use this extension for monitoring as well. Right?
>

real time monitoring? nope.


> 2) When I deal with some kind of hypervisor, I can always use 'virsh list
> --all' command in order to know which nodes are running and which aren't.
> How am I supposed to know which nodes are still alive in case of Ironic?
> IPMI? Again IPMI is not always available. And if IPMI is available, then
> why do we need heartbeat in Ironic agent?
>

Again, if there is no out-of-band power control, Ironic can't control the
power. Period.

As far as why is there a heartbeat in agent? Because some operations the
agent performs may take a long time, and so this allows ironic-conductor to
know the agent itself hasn't died (even if the node is still powered on).


Best,
Devananda
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