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<p class="MsoNormal"><span lang="EN-US">I just looked at savevm, and that is relatively simple code:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">qemu-kvm/savevm.c: do_savevm()<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">1.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">check if all disk support snapshots (call bdrv_can_snapshot())<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">2.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">vm_stop(RUN_STATE_SAVE_VM)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">3.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">Delete old snapshots of the same name<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">4.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">save the VM state<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">5.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">create the snapshots (call bdrv_snapshot_create())<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span lang="EN-US"><span style="mso-list:Ignore">6.)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US">resstart vm<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">For me, the interesting part is point 5, the call to bdrv_snapshot_create(),<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">which is defined in qemu-kvm/block.c:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">int bdrv_snapshot_create(BlockDriverState *bs,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> QEMUSnapshotInfo *sn_info)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">{<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> BlockDriver *drv = bs->drv;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (!drv)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return -ENOMEDIUM;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (drv->bdrv_snapshot_create)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return drv->bdrv_snapshot_create(bs, sn_info);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (bs->file)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return bdrv_snapshot_create(bs->file, sn_info);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return -ENOTSUP;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I wonder it is would be safe to call an external script to create the snapshot there?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Or is there still some data in the qemu block driver cache, or the host cache?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I guess I should ask that on the qemu-devel list instead?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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