<font size=2 face="sans-serif">>> </font><font size=2 color=#004080 face="Calibri"><b><i>So
maybe the problem isn’t having the flavors so much, but in how the user
currently has to specific an exact match from that list.</i></b></font>
<br><font size=2 color=#004080 face="Calibri"><b><i>If the user could say
“I want a flavor with these attributes” and then the system would find
a “best match” based on criteria set by the cloud admin then would that
be a more user friendly solution ? </i></b></font>
<br>
<br><font size=2 face="sans-serif">Interesting idea.. Thoughts how this
can be achieved?</font>
<br>
<br><font size=2 face="sans-serif">Alex<br>
</font>
<br>
<br>
<br>
<br><font size=1 color=#5f5f5f face="sans-serif">From:
</font><font size=1 face="sans-serif">"Day, Phil"
<philip.day@hp.com></font>
<br><font size=1 color=#5f5f5f face="sans-serif">To:
</font><font size=1 face="sans-serif">"OpenStack Development
Mailing List (not for usage questions)" <openstack-dev@lists.openstack.org>,
</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Date:
</font><font size=1 face="sans-serif">06/06/2014 12:38 PM</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Subject:
</font><font size=1 face="sans-serif">Re: [openstack-dev]
[nova] Proposal: Move CPU and memory allocation ratio out of scheduler</font>
<br>
<hr noshade>
<br>
<br>
<br><font size=2 color=#004080 face="Calibri"> </font>
<br><font size=2 face="Calibri"><b>From:</b> Scott Devoid [</font><a href=mailto:devoid@anl.gov><font size=2 face="Calibri">mailto:devoid@anl.gov</font></a><font size=2 face="Calibri">]
<b><br>
Sent:</b> 04 June 2014 17:36<b><br>
To:</b> OpenStack Development Mailing List (not for usage questions)<b><br>
Subject:</b> Re: [openstack-dev] [nova] Proposal: Move CPU and memory allocation
ratio out of scheduler</font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=2 face="Courier New">Not only live upgrades but also dynamic
reconfiguration.</font><font size=3 face="Times New Roman"> <br>
</font><font size=2 face="Courier New"><br>
Overcommitting affects the quality of service delivered to the cloud user.
In this situation in particular, as in many situations in general,
I think we want to enable the service provider to offer multiple qualities
of service. That is, enable the cloud provider to offer a selectable
level of overcommit. A given instance would be placed in a pool that
is dedicated to the relevant level of overcommit (or, possibly, a better
pool if the selected one is currently full). Ideally the pool sizes
would be dynamic. That's the dynamic reconfiguration I mentioned
preparing for.</font><font size=3 face="Times New Roman"> </font>
<br><font size=3 face="Times New Roman"> </font>
<br><font size=3 face="Times New Roman">+1 This is exactly the situation
I'm in as an operator. You can do different levels of overcommit with host-aggregates
and different flavors, but this has several drawbacks:</font>
<br><font size=2 face="sans-serif">1. </font><font size=3 face="Times New Roman">The
nature of this is <i>slightly</i> exposed to the end-user, through extra-specs
and the fact that two flavors cannot have the same name. One scenario we
have is that we want to be able to document our flavor names--what each
name means, but we want to provide different QoS standards for different
projects. Since flavor names must be unique, we have to create different
flavors for different levels of service. <i>Sometimes you do want to lie
to your users!</i></font>
<br><font size=2 color=#004080 face="Calibri"><b><i>[Day, Phil] I agree
that there is a problem with having every new option we add in extra_specs
leading to a new set of flavors. There are a number of changes
up for review to expose more hypervisor capabilities via extra_specs that
also have this potential problem. What I’d really like to
be able to ask for a s a user is something like “a medium instance with
a side order of overcommit”, rather than have to choose from a long list
of variations. I did spend some time trying to think of a
more elegant solution – but as the user wants to know what combinations
are available it pretty much comes down to needing that full list of combinations
somewhere. So maybe the problem isn’t having the flavors
so much, but in how the user currently has to specific an exact match from
that list.</i></b></font>
<br><font size=2 color=#004080 face="Calibri"><b><i>If the user could say
“I want a flavor with these attributes” and then the system would find
a “best match” based on criteria set by the cloud admin (for example
I might or might not want to allow a request for an overcommitted instance
to use my not-overcommited flavor depending on the roles of the tenant)
then would that be a more user friendly solution ? </i></b></font>
<br><font size=2 color=#004080 face="Calibri"><b><i> </i></b></font>
<br><font size=2 face="sans-serif">2. </font><font size=3 face="Times New Roman">If
I have two pools of nova-compute HVs with different overcommit settings,
I have to manage the pool sizes manually. Even if I use puppet to change
the config and flip an instance into a different pool, that requires me
to restart nova-compute. Not an ideal situation.</font>
<br><font size=2 color=#004080 face="Calibri"><b><i>[Day, Phil] If the
pools are aggregates, and the overcommit is defined by aggregate meta-data
then I don’t see why you need to restart nova-compute.</i></b></font>
<br><font size=3 color=#004080 face="Times New Roman">3.
</font><font size=3 face="Times New Roman">If I want to do anything
complicated, like 3 overcommit tiers with "good", "better",
"best" performance and allow the scheduler to pick "better"
for a "good" instance if the "good" pool is full, this
is very hard and complicated to do with the current system.</font>
<br><font size=2 color=#004080 face="Calibri"><b><i>[Day, Phil] Yep,
a combination of filters and weighting functions would allow you to do
this – its not really tied to whether the overcommit Is defined in the
scheduler or the host though as far as I can see. </i></b></font>
<br><font size=2 color=#004080 face="Calibri"> </font>
<br><font size=3 face="Times New Roman">I'm looking forward to seeing this
in nova-specs!</font>
<br><font size=3 face="Times New Roman">~ Scott</font><tt><font size=2>_______________________________________________<br>
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OpenStack-dev@lists.openstack.org<br>
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