[openstack-dev] [TripleO][Tuskar] Icehouse Requirements
Jay Dobies
jason.dobies at redhat.com
Thu Dec 12 21:48:28 UTC 2013
On 12/12/2013 04:25 PM, Keith Basil wrote:
> On Dec 12, 2013, at 4:05 PM, Jay Dobies wrote:
>
>>> Maybe this is a valid use case?
>>>
>>> Cloud operator has several core service nodes of differing configuration
>>> types.
>>>
>>> [node1] <-- balanced mix of disk/cpu/ram for general core services
>>> [node2] <-- lots of disks for Ceilometer data storage
>>> [node3] <-- low-end "appliance like" box for a specialized/custom core service
>>> (SIEM box for example)
>>>
>>> All nodes[1,2,3] are in the same deployment grouping ("core services)". As such,
>>> this is a heterogenous deployment grouping. Heterogeneity in this case defined by
>>> differing roles and hardware configurations.
>>>
>>> This is a real use case.
>>>
>>> How do we handle this?
>>
>> This is the sort of thing I had been concerned with, but I think this is just a variation on Robert's GPU example. Rather than butcher it by paraphrasing, I'll just include the relevant part:
>>
>>
>> "The basic stuff we're talking about so far is just about saying each
>> role can run on some set of undercloud flavors. If that new bit of kit
>> has the same coarse metadata as other kit, Nova can't tell it apart.
>> So the way to solve the problem is:
>> - a) teach Ironic about the specialness of the node (e.g. a tag 'GPU')
>> - b) teach Nova that there is a flavor that maps to the presence of
>> that specialness, and
>> c) teach Nova that other flavors may not map to that specialness
>>
>> then in Tuskar whatever Nova configuration is needed to use that GPU
>> is a special role ('GPU compute' for instance) and only that role
>> would be given that flavor to use. That special config is probably
>> being in a host aggregate, with an overcloud flavor that specifies
>> that aggregate, which means at the TripleO level we need to put the
>> aggregate in the config metadata for that role, and the admin does a
>> one-time setup in the Nova Horizon UI to configure their GPU compute
>> flavor."
>>
>
> Yes, the core services example is a variation on the above. The idea
> of _undercloud_ flavor assignment (flavor to role mapping) escaped me
> when I read that earlier.
>
> It appears to be very elegant and provides another attribute for Tuskar's
> notion of resource classes. So +1 here.
>
>
>> You mention three specific nodes, but what you're describing is more likely three concepts:
>> - Balanced Nodes
>> - High Disk I/O Nodes
>> - Low-End Appliance Nodes
>>
>> They may have one node in each, but I think your example of three nodes is potentially *too* simplified to be considered as proper sample size. I'd guess there are more than three in play commonly, in which case the concepts breakdown starts to be more appealing.
>
> Correct - definitely more than three, I just wanted to illustrate the use case.
I not sure I explained what I was getting at properly. I wasn't implying
you thought it was limited to just three. I do the same thing, simplify
down for discussion purposes (I've done so in my head about this very
topic).
But I think this may be a rare case where simplifying actually masks the
concept rather than exposes it. Manual feels a bit more desirable in
small sample groups but when looking at larger sets of nodes, the flavor
concept feels less odd than it does when defining a flavor for a single
machine.
That's all. :) Maybe that was clear already, but I wanted to make sure I
didn't come off as attacking your example. It certainly wasn't my
intention. The balanced v. disk machine thing is the sort of thing I'd
been thinking for a while but hadn't found a good way to make concrete.
>> I think the disk flavor in particular has quite a few use cases, especially until SSDs are ubiquitous. I'd want to flag those (in Jay terminology, "the disk hotness") as hosting the data-intensive portions, but where I had previously been viewing that as manual allocation, it sounds like the approach is to properly categorize them for what they are and teach Nova how to use them.
>>
>> Robert - Please correct me if I misread any of what your intention was, I don't want to drive people down the wrong path if I'm misinterpretting anything.
>
> -k
>
>
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