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<p class="MsoNormal" align="left" style="text-align:left"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif";color:black">Hi,
<o:p></o:p></span></p>
<p class="MsoNormal" align="left" style="text-align:left"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif";color:black">I noticed the following BP has been merged recently:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif";color:black"><a href="https://blueprints.launchpad.net/cinder/+spec/filtering-weighing-with-driver-supplied-functions">https://blueprints.launchpad.net/cinder/+spec/filtering-weighing-with-driver-supplied-functions</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif";color:black">i have read the related spec(</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif""><a href="http://git.openstack.org/cgit/openstack/cinder-specs/tree/specs/kilo/filtering-weighing-with-driver-supplied-functions.rst">http://git.openstack.org/cgit/openstack/cinder-specs/tree/specs/kilo/filtering-weighing-with-driver-supplied-functions.rst</a><span style="color:black">)</span>
and have got some questions.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">For my understanding, this BP brought two benefits:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">1) different admins can make various configurations on filtering/weighing (by editing equation in cinder.conf) to meet their various requirement; the
equation way itself is much more flexible than single capability scheduling.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">2) different backend drivers can take vendor specific evaluation;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">The BP seems focus more on the second target: letting drivers do evaluation by themselves. In the spec “editing equation in cinder.conf” is just an
example of driver implementation, “it is up to the driver to<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">determine how to generate the equations…Some choices a driver has are to use values defined in cinder.conf, hard-code the values in the driver or not
implement the properties at all”. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">But I think it is also a fact that a lot of devices have common capabilities/attributes(even thin-provisionning can take as a common attribute today),
so can we make the “editing equation in cinder.conf” a base/common implementation to this new scheduler?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">Which means:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">1) this new scheduler has a built-in implementation of filter/goodness funtion;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">2) drivers can supply their own functions as they do now; If a driver do not supply one, built-in function will work;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">Another question:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">Can we make different volume-types associated with different evaluation rule (means different filter/goodness function pair)? I think this is also very
useful.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial Unicode MS","sans-serif"">Thanks.<o:p></o:p></span></p>
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