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<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D">Just for live snapshot, my understanding is the instance state will not be saved.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Cristian Tomoiaga [mailto:ctomoiaga@gmail.com]
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<b>Sent:</b> Sunday, April 20, 2014 6:20 PM<br>
<b>To:</b> openstack-dev@lists.openstack.org<br>
<b>Subject:</b> [openstack-dev] [nova] Nova and LVM thin support<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Hello everyone,<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Before going any further with my implementation I would like to ask the community about the LVM thin support in Nova (not Cinder). <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">The current implementation of the LVM backend does not support thin LVs.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Does anyone believe it is a good idea to add support for this in Nova ? (I plan on adding support for my implementation anyway).<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">I would also like to know where Red Hat stands on this, since they are primarily working on LVM.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">I've seen that LVM thin would be supported in RHEL 7 (?) so we may consider the thin target stable enough for production in Juno (cinder already has support for this since last year).<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">I know there was ongoing work to bring a common storage library implementation to oslo or nova directly (Cinder's Brick library) but I heard nothing new for some time now. Maybe John Griffith has some thoughts on this.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">The reasons why support for LVM thin would be a nice addition should be well known especially to people working with LVM.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Another question is related to how Nova treats snapshots when LVM is used as a backend (I hope I didn't miss anything in the code):<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Right now if we can't do a live snapshot, the instance state (memory) is being saved (libvirt </span><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana","sans-serif";color:black">virDomainManagedSave</span><span lang="EN-US">)
and qemu-img is used to backup the instance disk(s). After that we resume the instance.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Can we insert code to snapshot the instance disk so we only keep the instance offline just for a memory dump and copy the disk content from the snapshot created ?<br clear="all">
<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">-- <br>
Regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Cristian Tomoiaga<o:p></o:p></span></p>
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