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<div class="moz-cite-prefix">On 26/11/15 15:55, 少合冯 wrote:<br>
</div>
<blockquote
cite="mid:CAGV=wNNfKj35Qfo4ZSaKAev4P8YypZfTvVtOCPMx60Cevsb+kw@mail.gmail.com"
type="cite">
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<div>Hi all, </div>
We want to support xbzrle compress for live migration.
<div><br>
</div>
<div>Now there are 3 options,</div>
<div>1. add the enable flag in nova.conf. </div>
<div> such as<span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)"> </span><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)">a
dedicated 'live_migration_compression=on|off" parameter in </span>nova.conf.</div>
<div> And nova simply enable it.</div>
<div> seems not good.</div>
<div>2. add a parameters in live migration API.</div>
<div><br>
</div>
<div>
<div>A new array compress will be added as optional, the
json-schema as below::</div>
<div><br>
</div>
<div> {</div>
<div> 'type': 'object',</div>
<div> 'properties': {</div>
<div> 'os-migrateLive': {</div>
<div> 'type': 'object',</div>
<div> 'properties': {</div>
<div> 'block_migration': parameter_types.boolean,</div>
<div> 'disk_over_commit': parameter_types.boolean,</div>
<div> 'compress': {</div>
<div> 'type': 'array',</div>
<div> 'items': ["xbzrle"],</div>
<div> },</div>
<div> 'host': host</div>
<div> },</div>
<div> 'additionalProperties': False,</div>
<div> },</div>
<div> },</div>
<div> 'required': ['os-migrateLive'],</div>
<div> 'additionalProperties': False,</div>
<div> }</div>
</div>
<div><br>
</div>
<div><br>
</div>
<div>3. <span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)"> </span><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)">dynamically
choose when to activate</span><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)"> xbzrle
compress for live migration.</span></div>
<div><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)">
This is the best. </span></div>
<div><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)">
</span><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)"> xbzrle</span><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)"> really
wants to be used if the network is not able to keep up with
the dirtying rate of the guest RAM.</span></div>
<div><span
style="color:rgb(0,0,0);font-family:sans-serif;background-color:rgb(229,236,249)">
But how do I check the coming migration fit this
situation？</span></div>
<div>
<p
style="margin-top:0px;margin-bottom:0px;padding-top:0.5em;padding-bottom:0.5em;color:rgb(0,0,0);font-family:sans-serif"><span class="" style="white-space:pre;font-family:'Lucida Console','Lucida Sans Typewriter',Monaco,monospace"> </span></p>
</div>
<div><br>
</div>
<div>REF:</div>
<div><a moz-do-not-send="true"
href="https://review.openstack.org/#/c/248465/">https://review.openstack.org/#/c/248465/</a><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div>BR</div>
<div>Shaohe Feng</div>
</div>
</blockquote>
<br>
Feels to me that this is too implementation dependent to be exposed
in API. I've seen elsewhere<br>
discussion about removing the block migrate and disk over commit
parameters, the idea being it<br>
would figure out the type of migration for itself and over commit is
not needed anymore.<br>
<br>
Seems to me the prevailing view is that we should get live migration
to figure out the best setting for<br>
itself where possible. There was discussion of being able have a
default policy setting that will allow<br>
the operator to define balance between speed of migration and impact
on the instance. This could be<br>
a global default for the cloud with overriding defaults per
aggregate, image, tenant and instance as<br>
well as the ability to vary the setting during the migration
operation.<br>
<br>
Seems to me that items like compression should be set in
configuration files based on what works best<br>
given the cloud operator's environment?<br>
<pre class="moz-signature" cols="72">--
Paul Carlton
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