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<p class="MsoNormal"><span style="color:#1F497D">Answers in line. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Trivedi, Narendra [mailto:Narendra.Trivedi@savvis.com]
<br>
<b>Sent:</b> Tuesday, November 12, 2013 9:24 AM<br>
<b>To:</b> openstack@lists.openstack.org<br>
<b>Subject:</b> [Openstack] Cinde muti-backend feature<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi All, <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Could someone please explain the Cinder multi-backends feature (as of Havana)? Specifically, I had the following questions:
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">1)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Can I attach multiple physical storage backends (let’s say one all SSD, another all SATA for instance) to a single host?<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Yes. A typical cinder.conf would look like:<o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">enabled_backends=lvmdriver-3par,lvmdriver-netapp
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">auth_strategy = keystone
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">scheduler_driver=cinder.scheduler.filter_scheduler.FilterScheduler
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">[lvmdriver-3par]
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_group=cinder-volumes-3par
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_driver=cinder.volume.drivers.lvm.LVMISCSIDriver
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_backend_name=LVM_3par
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">[lvmdriver-netapp]
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_group=cinder-volumes-netapp
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_driver=cinder.volume.drivers.lvm.LVMISCSIDriver
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:13.0pt"><span style="font-size:10.0pt;font-family:"Courier New";color:#333333">volume_backend_name=LVM_netapp
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#333333"><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"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">2)<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>How does migration between different multiple backends work? Let’s say the an SSD volume is attached to a VM I want to migrate all the data in the SSD volume to a SATA volume without bringing down the interface. Do I have to manually
mount/un-mount the persistent volume to the instance- how do paths are maintained? For instance, let’s say the persistent volume was /dev/vdx mounted to /mnt/vol0 , how does it re-appear ?
<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">As far as I know, you have to manually copy it from one block storage to the other by mounting the new one.
<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks a lot in advance!<o:p></o:p></p>
<p class="MsoNormal">Narendra <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""><br>
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