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<p class="MsoNormal">Putting the image on tmpfs cut the snapshot time down by quite a bit. It didn’t do much for the restore time, probably because the images I’m using fit in the file cache already.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Now I’m going to look in to profiling qemu to see where it’s spending all of its time.</p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Gary Jackson</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Doug Hughes <doug.hughes@keystonenap.com><br>
<b>Date: </b>Tuesday, September 19, 2017 at 12:59 PM<br>
<b>To: </b>"Jackson, Gary L." <Gary.Jackson@jhuapl.edu>, "libvirt-users@redhat.com" <libvirt-users@redhat.com><br>
<b>Subject: </b>Re: [libvirt-users] Rollback to running VM<o:p></o:p></span></p>
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<p>I would estimate you are bounded by memory bandwidth (GB/sec - so not much, but proportional to memory size) and disk bandwidth. So, using SSD will help for certain vs spinning. I'm not sure about the catch-22 implicit with using a ramdisk, but since the
ramdisk should be previsioned from the host to the guest, it seems like it should work.<o:p></o:p></p>
<p>There may be other bottlenecks in drivers, etc. Not in my knowledge domain.<o:p></o:p></p>
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<p class="MsoNormal">On 9/19/2017 12:53 PM, Jackson, Gary L. wrote:<o:p></o:p></p>
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<p class="MsoNormal">Thanks! The vanilla snapshot-create-as and revert commands work just exactly the way I’d want them to. I’d gotten a bit confused by the documentation and went down a rabbit hole with external snapshots.<o:p></o:p></p>
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<p class="MsoNormal">Is there any way to make the snapshot and restore faster, like maybe by a decimal order of magnitude? For example, will PXE booting the VM and running it entirely off of a RAM disk and also using a RAM disk for the backing store help?<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">-- </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Gary Jackson</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Doug Hughes
</span><a href="mailto:doug.hughes@keystonenap.com"><span style="font-size:12.0pt"><doug.hughes@keystonenap.com></span></a><span style="font-size:12.0pt;color:black"><br>
<b>Date: </b>Tuesday, September 19, 2017 at 11:25 AM<br>
<b>To: </b>"Jackson, Gary L." </span><a href="mailto:Gary.Jackson@jhuapl.edu"><span style="font-size:12.0pt"><Gary.Jackson@jhuapl.edu></span></a><span style="font-size:12.0pt;color:black">,
</span><a href="mailto:libvirt-users@redhat.com"><span style="font-size:12.0pt">"libvirt-users@redhat.com"</span></a><span style="font-size:12.0pt;color:black">
</span><a href="mailto:libvirt-users@redhat.com"><span style="font-size:12.0pt"><libvirt-users@redhat.com></span></a><span style="font-size:12.0pt;color:black"><br>
<b>Subject: </b>Re: [libvirt-users] Rollback to running VM</span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">According to this page: <a href="https://wiki.libvirt.org/page/Snapshots">
https://wiki.libvirt.org/page/Snapshots</a><br>
It saves complete memory state, or crash-consistent disk state, but not both.<br>
<br>
You probably want to test it thoroughly and see how it does. I only use the disk-consistent snapshots.<o:p></o:p></p>
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<p class="MsoNormal">On 9/19/2017 11:17 AM, Jackson, Gary L. wrote:<o:p></o:p></p>
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<pre>Will snapshot-revert restore the processor and memory state of the VM as it was at the time of the snapshot?<o:p></o:p></pre>
<pre> <o:p></o:p></pre>
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<p class="MsoNormal">Doug Hughes<br>
Keystone NAP<br>
Fairless Hills, PA<br>
1.844.KEYBLOCK (539.2562)<o:p></o:p></p>
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