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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Hi Avishay-san,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">Thank you for your comment. I commented in-line.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">>></span> I'm sorry, but I remain unconvinced. Is there a customer demand for this feature?<span style="mso-fareast-language:JA"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";mso-fareast-language:JA">Currently, we do not have specific customer’s demand for this feature.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";mso-fareast-language:JA">But I believe this feature provides benefits to both customers and cloud providers.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">>></span> If you'd like, feel free to add this topic to a Cinder weekly meeting agenda,<span style="mso-fareast-language:JA"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">>></span> and join the meeting so that we can have an interactive discussion.<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">If possible, I would like to continue discussions on the ML.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">Mitsuhiro Tanino <<a href="mitsuhiro.tanino@hds.com"><span style="color:blue">mitsuhiro.tanino@hds.com</span></a>><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA">
<b>HITACHI DATA SYSTEMS<o:p></o:p></b></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA"> c/o Red Hat, 314 Littleton Road, Westford, MA 01886<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><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""> Avishay Traeger [mailto:avishay@stratoscale.com]
<br>
<b>Sent:</b> Sunday, May 25, 2014 3:06 AM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Cc:</b> Tomoki Sekiyama<br>
<b>Subject:</b> Re: [openstack-dev] [Cinder] Support LVM on a shared LU<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Hello Mitsuhiro,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">I'm sorry, but I remain unconvinced. Is there a customer demand for this feature?<br>
If you'd like, feel free to add this topic to a Cinder weekly meeting agenda, and join the meeting so that we can have an interactive discussion.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a href="https://wiki.openstack.org/wiki/CinderMeetings">https://wiki.openstack.org/wiki/CinderMeetings</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Thanks,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Avishay<o:p></o:p></p>
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<o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On Sat, May 24, 2014 at 12:31 AM, Mitsuhiro Tanino <<a href="mailto:mitsuhiro.tanino@hds.com" target="_blank">mitsuhiro.tanino@hds.com</a>> wrote:<o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Hi Avishay-san,</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Thank you for your review and comments for my proposal. I commented in-line.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>>So the way I see it, the value here is a generic driver that can work with any storage. The downsides:</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">A generic driver for any storage is an one of benefit.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">But main benefit of proposed driver is as follows.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">- Reduce hardware based storage workload by offloading the workload to software based volume operation.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Conventionally, operations to an enterprise storage such as volume creation, deletion, snapshot, etc</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">are only permitted system administrator and they handle these operations after carefully examining.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">In OpenStack cloud environment, every user have a permission to execute these storage operations</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">via cinder. As a result, workloads of storages have been increasing and it is difficult to manage</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">the workloads.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in">
<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">If we have two drivers in regards to a storage, we can use both way as the situation demands.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Ex.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> As for "Standard" type storage, use proposed software based LVM cinder driver.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> As for "High performance" type storage, use hardware based cinder driver.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">As a result, we can offload the workload of standard type storage from physical storage to cinder host.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>>1. The admin has to manually provision a very big volume and attach it to the Nova and Cinder hosts.
</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> Every time a host is rebooted,</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">I thinks current FC-based cinder drivers using scsi scan to find created LU.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"># echo "- - -" > /sys/class/scsi_host/host#/scan</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">The admin can find additional LU using this, so host reboot are not required.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> or introduced, the admin must do manual work. This is one of the things OpenStack should be trying
</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> to avoid. This can't be automated without a driver, which is what you're trying to avoid.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Yes. Some admin manual work is required and can’t be automated.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">I would like to know whether these operations are acceptable range to enjoy benefits from</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">my proposed driver.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>>2. You lose on performance to volumes by adding another layer in the stack.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">I think this is case by case. When user use a cinder volume for DATA BASE, they prefer</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">raw volume and proposed driver can’t provide raw cinder volume.
</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">In this case, I recommend "High performance" type storage.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">LVM is a default feature in many Linux distribution. Also LVM is used many enterprise</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">systems and I think there is not critical performance loss.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>>3. You lose performance with snapshots - appliances will almost certainly have more efficient snapshots</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> than LVM over network (consider that for every COW operation, you are reading synchronously over the network).</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> (Basically, you turned your fully-capable storage appliance into a dumb JBOD)</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">I agree that storage has efficient COW snapshot feature, so we can create new Boot Volume</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">from glance quickly. In this case, I recommend "High performance" type storage.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">LVM can’t create nested snapshot with shared LVM now. Therefore, we can’t assign</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">writable LVM snapshot to instances.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Is this answer for your comment?</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> In short, I think the cons outweigh the pros. Are there people deploying OpenStack who would deploy
</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> their storage like this?</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Please consider above main benefit.</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Regards,</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Mitsuhiro Tanino <<a href="http://mitsuhiro.tanino@hds.com" target="_blank">mitsuhiro.tanino@hds.com</a>></span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">
<b>HITACHI DATA SYSTEMS</b></span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> c/o Red Hat, 314 Littleton Road, Westford, MA 01886</span><o:p></o:p></p>
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<span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
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<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""> Avishay Traeger [mailto:<a href="mailto:avishay@stratoscale.com" target="_blank">avishay@stratoscale.com</a>]
<br>
<b>Sent:</b> Wednesday, May 21, 2014 4:36 AM<br>
<b>To:</b> OpenStack Development Mailing List (not for usage questions)<br>
<b>Cc:</b> Tomoki Sekiyama<br>
<b>Subject:</b> Re: [openstack-dev] [Cinder] Support LVM on a shared LU</span><o:p></o:p></p>
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<o:p></o:p></p>
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So the way I see it, the value here is a generic driver that can work with any storage. The downsides:<o:p></o:p></p>
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1. The admin has to manually provision a very big volume and attach it to the Nova and Cinder hosts. Every time a host is rebooted, or introduced, the admin must do manual work. This is one of the things OpenStack should be trying to avoid. This can't be automated
without a driver, which is what you're trying to avoid.<o:p></o:p></p>
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2. You lose on performance to volumes by adding another layer in the stack.<o:p></o:p></p>
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3. You lose performance with snapshots - appliances will almost certainly have more efficient snapshots than LVM over network (consider that for every COW operation, you are reading synchronously over the network).<o:p></o:p></p>
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<o:p></o:p></p>
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(Basically, you turned your fully-capable storage appliance into a dumb JBOD)<o:p></o:p></p>
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<o:p></o:p></p>
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In short, I think the cons outweigh the pros. Are there people deploying OpenStack who would deploy their storage like this?<o:p></o:p></p>
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<o:p></o:p></p>
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Thanks,<br>
Avishay<o:p></o:p></p>
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On Tue, May 20, 2014 at 6:31 PM, Mitsuhiro Tanino <<a href="mailto:mitsuhiro.tanino@hds.com" target="_blank">mitsuhiro.tanino@hds.com</a>> wrote:<o:p></o:p></p>
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Hello All,<o:p></o:p></p>
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<o:p></o:p></p>
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I’m proposing a feature of LVM driver to support LVM on a shared LU.<o:p></o:p></p>
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The proposed LVM volume driver provides these benefits.<br>
- Reduce hardware based storage workload by offloading the workload to software based volume operation.<br>
- Provide quicker volume creation and snapshot creation without storage workloads.<br>
- Enable cinder to any kinds of shared storage volumes without specific cinder storage driver.<o:p></o:p></p>
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- Better I/O performance using direct volume access via Fibre channel.<o:p></o:p></p>
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<o:p></o:p></p>
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In the attachment pdf, following contents are explained.<o:p></o:p></p>
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1. Detail of Proposed LVM volume driver<o:p></o:p></p>
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1-1. Big Picture<o:p></o:p></p>
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1-2. Administrator preparation<o:p></o:p></p>
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1-3. Work flow of volume creation and attachment<o:p></o:p></p>
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2. Target of Proposed LVM volume driver<o:p></o:p></p>
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3. Comparison of Proposed LVM volume driver<o:p></o:p></p>
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<o:p></o:p></p>
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Could you review the attachment?<o:p></o:p></p>
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Any comments, questions, additional ideas would be appreciated.<o:p></o:p></p>
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<o:p></o:p></p>
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<o:p></o:p></p>
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Also there are blueprints, wiki and patches related to the slide.<o:p></o:p></p>
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<a href="https://blueprints.launchpad.net/cinder/+spec/lvm-driver-for-shared-storage" target="_blank">https://blueprints.launchpad.net/cinder/+spec/lvm-driver-for-shared-storage</a><o:p></o:p></p>
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<a href="https://blueprints.launchpad.net/nova/+spec/lvm-driver-for-shared-storage" target="_blank">https://blueprints.launchpad.net/nova/+spec/lvm-driver-for-shared-storage</a><o:p></o:p></p>
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<a href="https://wiki.openstack.org/wiki/Cinder/NewLVMbasedDriverForSharedStorageInCinder" target="_blank">https://wiki.openstack.org/wiki/Cinder/NewLVMbasedDriverForSharedStorageInCinder</a><o:p></o:p></p>
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<a href="https://review.openstack.org/#/c/92479/" target="_blank">https://review.openstack.org/#/c/92479/</a><o:p></o:p></p>
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<a href="https://review.openstack.org/#/c/92443/" target="_blank">https://review.openstack.org/#/c/92443/</a><o:p></o:p></p>
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<span style="color:black"> </span><o:p></o:p></p>
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<span style="color:black">Regards,</span><o:p></o:p></p>
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<span style="color:black">Mitsuhiro Tanino <<a href="http://mitsuhiro.tanino@hds.com" target="_blank">mitsuhiro.tanino@hds.com</a>></span><o:p></o:p></p>
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<span style="color:black"> <b>HITACHI DATA SYSTEMS</b></span><o:p></o:p></p>
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<span style="color:black"> c/o Red Hat, 314 Littleton Road, Westford, MA 01886</span><o:p></o:p></p>
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