[Users] RFE: A manual way of saying that only hostA in a DC shall be used as proxy for power commands

[Itamar Heim]

On 07/30/2012 08:56 AM, Karli Sjöberg wrote:
>
> 28 jul 2012 kl. 14.11 skrev Moti Asayag:
>
>> On 07/26/2012 02:53 PM, Karli Sjöberg wrote:
>>> Hi,
>>>
>>> In my DC, I have three hosts added:
>>>
>>> hostA
>>> hostB
>>> hostC
>>>
>>> I want a way to force only to use hostA as a proxy for power commands.
>>
>> The algorithm of selection a host to act as a proxy for PM commands is
>> quite naive: any host from the system with status UP.
>>
>> You can see how it is being selected in FencingExecutor.FindVdsToFence()
>> from
>> ovirt-engine/backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/FencingExecutor.java
>>
>> There is no other algorithm for the selection at the moment.
>>
>> How would you handle a case in which hostA isn't responsive ? Wouldn't
>> you prefer trying to perform the fencing using other available host ?
>
>
> Let me explain a little to make you better understand my reasoning
> behind this configuration.
>
> We work with segmented, separated networks. One network for public
> access, one for storage traffic, one for management and so on. That
> means that if the nodes themselves have to do their own
> power-management, the nodes would require three interfaces each, and the
> metal we are using for hosts just don´t have that. But if we can use the
> engine to do that, the hosts would only require two interfaces, which
> most 1U servers are equipped with as standard (plus one
> iLO/IPMI/whatev), so we can use them as hosts without issue. Then the
> backend has one extra interface that it can use to communicate over the
> power management network to the respective service processor with.
>
> Is there a "better" way to achieve what we are aiming for? Ideally, I
> would like to set up the two NICs in a bond and create VLAN-interfaces
> on top of that bond. That way, I can have as many virtual interfaces as
> I want without having more than two physical NICs, but I haven´t been
> able to find a good HOWTO explaining the process.
>

I think there is a difference between:
1. allowing engine to fence
2. allowing to choose fencing host per cluster (or per host)

it sounds like you actually want #1, but can live with #2, by installing 
the engine as a host as well.