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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">after some more thinking, this is also wrong. I would be really great to<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">have some documentation about that? How does read/write during recovery<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">works exactly.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I first though we can simply reject reads. For writes, we can reject them<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">until we start object recovery. After that point we cache written data (but<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">still reject reads). When we have received the whole object we merge with<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">write cache. But that is not the way it works?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">- Dietmar<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;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""> Dietmar Maurer
<br>
<b>Sent:</b> Freitag, 20. Juli 2012 17:59<br>
<b>To:</b> Dietmar Maurer; Liu Yuan<br>
<b>Cc:</b> Chris Webb; sheepdog@lists.wpkg.org<br>
<b>Subject:</b> RE: [sheepdog] [PATCH] sheep: add a kill node operation<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I guess I finally got it ;-) We only get slow response for a few objects where we<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">received an epoch mismatch – most request are directed to a living node which<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">already have the object?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">That still means that IO on the KVM side is extremely slow during (2h) recovery?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;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""> Liu Yuan
<a href="mailto:[mailto:namei.unix@gmail.com]">[mailto:namei.unix@gmail.com]</a> <br>
<b>Sent:</b> Freitag, 20. Juli 2012 16:18<br>
<b>To:</b> Dietmar Maurer<br>
<b>Cc:</b> <a href="mailto:sheepdog@lists.wpkg.org">sheepdog@lists.wpkg.org</a>; Chris Webb<br>
<b>Subject:</b> RE: [sheepdog] [PATCH] sheep: add a kill node operation<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>nope, at most dozens of sec as I observed<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"MS Gothic"">在</span> 2012-7-20 PM10:04<span style="font-family:"MS Gothic"">，</span>"Dietmar Maurer" <<a href="mailto:dietmar@proxmox.com">dietmar@proxmox.com</a>><span style="font-family:"MS Gothic"">写道：</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">> > Let's assume a complete recovery takes about 2 hours. Does that mean<br>
> > my VMs are blocked for 2 hours (instead of continue operation on other<br>
> nodes)?<br>
> ><br>
><br>
> This is actually why we spend lots of lines in recovery and IO patch, there are<br>
> some mechanism, such as request retry, oid scheduling that tries to complete<br>
> any request in a very short period because IOs from VM are timeouted by<br>
> guest kernel, for e.g,<br>
> 120 seconds for Linux kernel.<br>
<br>
So if a VM access such object, it would block for 2 hours (confused)?<o:p></o:p></p>
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