On 08/26/2016 09:20 AM, Ed Leafe wrote:
On Aug 25, 2016, at 3:19 PM, Andrew Laski <and...@lascii.com> wrote:
One other thing to note is that while a flavor constrains how much local
disk is used it does not constrain volume size at all. So a user can
specify an ephemeral/swap disk <= to what the flavor provides but can
have an arbitrary sized root disk if it's a remote volume.
This kind of goes to the heart of the argument against flavors being the sole
source of truth for a request. As cloud evolves, we keep packing more and more
stuff into a concept that was originally meant to only divide up resources that
came bundled together (CPU, RAM, and local disk). This hasn’t been a good
solution for years, and the sooner we start accepting that a request can be
much more complex than a flavor can adequately express, the better.
If we have decided that remote volumes are a good thing (I don’t think there’s
any argument there), then we should treat that part of the request as being as
fundamental as a flavor. We need to make the scheduler smarter so that it
doesn’t rely on flavor as being the only source of truth.
The first step to improving Nova is admitting we have a problem. :)
FWIW, I agree with you on the above. The issue I had with the proposed
patches was that they would essentially be a hack for a short period of
time until the resource providers work standardized the way that DISK_GB
resources were tracked -- including for providers of shared disk storage.
I've long felt that flavors as a concept should be, as Chris so adeptly
wrote, "UI furniture" and should be decomposed into their requisite
lists of resource amounts, required traits and preferred traits and that
those decomposed parts are what should be passed to the Compute API, not
a flavor ID.
But again, we're actively changing all this code in the resource
providers and qualitative traits patches so I warned about adding more
code that was essentially just a short-lived hack. I'd be OK adding the
hack code if there were some big bright WARNINGs placed in there that
likely the code would be removed in Ocata.
-jay
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