blog/Fixing_an_hanging_debian_installer_for_Debian_Edu.html

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   6     <title>Petter Reinholdtsen: Fixing an hanging debian installer for Debian Edu</title>
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  14  <h1>
  15      <a href="http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
  16
  17  </h1>
  18
  19 </div>
  20
  21
  22     <div class="entry">
  23       <div class="title">Fixing an hanging debian installer for Debian Edu</div>
  24       <div class="date"> 3rd January 2012</div>
  25       <div class="body"><p>During christmas, I have been working getting the next version of
  26 <a href="http://www.skolelinux.org/">Debian Edu / Skolelinux</a> ready
  27 for release.  The initial problem I looked at was particularly
  28 interesting.</p>
  29
  30 <P>The installer would hang at the end when it was doing it
  31 post-installation configuration, and whatevery I did to try to find
  32 the cause and fix it always worked while I tested it, but never when I
  33 integrated it into the installer and ran the installation from
  34 scratch.  I would try to restart processes, close file descriptors,
  35 remove or create files, and the installer would always unblock and
  36 wrap up its tasks.</p>
  37
  38 <p>Eventually the cause was found.  The kernel was simply running out
  39 of entropy, causing the Kerberos setup to hang waiting for more.
  40 Pressing keys was adding entropy to the kernel, and thus all my tries
  41 to fix the problem worked not because what I was typing to fix it, but
  42 because I was typing.</P>
  43
  44 <p>The fix I implemented was to add a background process looking at
  45 the level of entropy in the kernel (by checking
  46 /proc/sys/kernel/random/entropy_avail), and if it was too small, the
  47 installer will flush the kernel file buffers and do 'find /' to
  48 generate some disk IO.  Disk IO generate entropy in the kernel, and is
  49 one of the few things that can be initated from within the system to
  50 generate entropy.</p>
  51
  52 <p>The fix is in
  53 <a href="http://wiki.debian.org/DebianEdu/Documentation/Squeeze/Installation">beta1
  54 of the Debian Edu/Squeeze</a> version, and we
  55 <a href="http://wiki.debian.org/DebianEdu">welcome more testers and
  56 developers</a>.  We plan to release beta2 this weekend.</p>
  57 </div>
  58
  59       <div class="tags">Tags: <a href="http://people.skolelinux.org/pere/blog/tags/debian edu">debian edu</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>.</div>
  60
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  68
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  70
  71 <h2>Archive</h2>
  72 <ul>
  73
  74 <li>2016
  75 <ul>
  76
  77 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/01/">January (3)</a></li>
  78
  79 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/02/">February (2)</a></li>
  80
  81 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/03/">March (3)</a></li>
  82
  83 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/04/">April (8)</a></li>
  84
  85 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/05/">May (8)</a></li>
  86
  87 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/06/">June (2)</a></li>
  88
  89 <li><a href="http://people.skolelinux.org/pere/blog/archive/2016/07/">July (1)</a></li>
  90
  91 </ul></li>
  92
  93 <li>2015
  94 <ul>
  95
  96 <li><a href="http://people.skolelinux.org/pere/blog/archive/2015/01/">January (7)</a></li>
  97
  98 <li><a href="http://people.skolelinux.org/pere/blog/archive/2015/02/">February (6)</a></li>
  99
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 117
 118 <li><a href="http://people.skolelinux.org/pere/blog/archive/2015/12/">December (3)</a></li>
 119
 120 </ul></li>
 121
 122 <li>2014
 123 <ul>
 124
 125 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/01/">January (2)</a></li>
 126
 127 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/02/">February (3)</a></li>
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 129 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/03/">March (8)</a></li>
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 131 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/04/">April (7)</a></li>
 132
 133 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/05/">May (1)</a></li>
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 135 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/06/">June (2)</a></li>
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 137 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/07/">July (2)</a></li>
 138
 139 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/08/">August (2)</a></li>
 140
 141 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/09/">September (5)</a></li>
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 143 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/10/">October (6)</a></li>
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 145 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/11/">November (3)</a></li>
 146
 147 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/12/">December (5)</a></li>
 148
 149 </ul></li>
 150
 151 <li>2013
 152 <ul>
 153
 154 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/01/">January (11)</a></li>
 155
 156 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/02/">February (9)</a></li>
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 170 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/09/">September (5)</a></li>
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 172 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/10/">October (7)</a></li>
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 174 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/11/">November (9)</a></li>
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 176 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/12/">December (3)</a></li>
 177
 178 </ul></li>
 179
 180 <li>2012
 181 <ul>
 182
 183 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
 184
 185 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
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 205 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
 206
 207 </ul></li>
 208
 209 <li>2011
 210 <ul>
 211
 212 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
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 214 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
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 232 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
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 234 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
 235
 236 </ul></li>
 237
 238 <li>2010
 239 <ul>
 240
 241 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
 242
 243 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
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 263 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
 264
 265 </ul></li>
 266
 267 <li>2009
 268 <ul>
 269
 270 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
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 272 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
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 291
 292 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
 293
 294 </ul></li>
 295
 296 <li>2008
 297 <ul>
 298
 299 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
 300
 301 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
 302
 303 </ul></li>
 304
 305 </ul>
 306
 307
 308
 309 <h2>Tags</h2>
 310 <ul>
 311
 312  <li><a href="http://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (13)</a></li>
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