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<pre>>><i> -----Original Message-----<o:p></o:p></i></pre>
<pre>>><i> From: Vishvananda Ishaya [mailto:<a href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev">vishvananda at gmail.com</a>]<o:p></o:p></i></pre>
<pre>>><i> Sent: Tuesday, December 18, 2012 6:46 AM<o:p></o:p></i></pre>
<pre>>><i> To: OpenStack Development Mailing List<o:p></o:p></i></pre>
<pre>>><i> Subject: Re: [openstack-dev] Booting multiple instances with block device<o:p></o:p></i></pre>
<pre>>><i> mapping<o:p></o:p></i></pre>
<pre>>><i> <o:p></o:p></i></pre>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">On Dec 18, 2012, at 8:41 AM, "Karajgi, Rohit" <<a href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev">Rohit.Karajgi at nttdata.com</a>> wrote:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">><i>
<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">><i> Currently I don’t think there is any logic to map a list of block device mappings to multiple instances if the count is > 1.<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">><i> For eg: If a user requests to create 3 instances and passes 3 volumes to be booted from, should there be a 1:1 mapping<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">><i> between the instance list and the volume list?<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">><i>
<o:p></o:p></i></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New"">>> I don't think we should support multiple boot from volumes. If someone needs to specify a different volume for each instance they should launch each request
<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New"">>> separately. If you are referring to booting from a snapshot, I believe the code in manager updates the block device mapping for each instance when it creates
<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New"">>> the volume.<o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New"">>> Vish<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></i></p>
<p class="MsoNormal"><b><i><span style="color:#1F497D">[Rohit Karajgi] </span></i></b><span style="color:#1F497D">Thanks Vish for your responses. I think the way block device mappings should be used in Nova is slightly ambiguous, and there needs to be some
validation in Nova API to remove this ambiguity. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">If we won’t support multiple boot from volumes, i.e multiple instances and multiple bdms, then the API should reject requests if it finds invalid user input.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">For example, I think validations need to be added for the following use cases (OSAPI):<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">Boot multiple instances using a single BDM volume: Now, just one instance boots with the volume attached to it. The rest of the instances land up in ERROR state, and user has to clean them up.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">Boot multiple instances using a list of BDM volumes (on the same or different mount points): Now, just one instance boots up with the all the volumes attached to it. The rest of the instances are in
ERROR and need to be cleaned up. Such a request should get rejected.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Questions:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">What should happen when user passes both a bootable volume_id
<i>and</i> a snapshot_id in the same block device mapping? Is this allowed?<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">In AWS EC2 API, volume ID’s are ignored/rejected in block device mapping. Instances can only be booted from snapshot (in which case a volume is created). Is the Openstack EC2 API a deviation from the
AWS EC2 implementation? Our cloud.py seems to not ignore volume id’s and use them to boot instances. What is the correct behavior here?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I would like to submit patches to have these validations in place if you deem them necessary. Thoughts?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Regards,</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Rohit
</span></b><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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