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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  62     </div>
  63
  64
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  67     <div id="sidebar">
  68
  69
  70
  71 <h2>Archive</h2>
  72 <ul>
  73
  74 <li>2015
  75 <ul>
  76
  77 <li><a href="http://people.skolelinux.org/pere/blog/archive/2015/01/">January (3)</a></li>
  78
  79 </ul></li>
  80
  81 <li>2014
  82 <ul>
  83
  84 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/01/">January (2)</a></li>
  85
  86 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/02/">February (3)</a></li>
  87
  88 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/03/">March (8)</a></li>
  89
  90 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/04/">April (7)</a></li>
  91
  92 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/05/">May (1)</a></li>
  93
  94 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/06/">June (2)</a></li>
  95
  96 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/07/">July (2)</a></li>
  97
  98 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/08/">August (2)</a></li>
  99
 100 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/09/">September (5)</a></li>
 101
 102 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/10/">October (6)</a></li>
 103
 104 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/11/">November (3)</a></li>
 105
 106 <li><a href="http://people.skolelinux.org/pere/blog/archive/2014/12/">December (5)</a></li>
 107
 108 </ul></li>
 109
 110 <li>2013
 111 <ul>
 112
 113 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/01/">January (11)</a></li>
 114
 115 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/02/">February (9)</a></li>
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 120
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 122
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 124
 125 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/07/">July (7)</a></li>
 126
 127 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/08/">August (3)</a></li>
 128
 129 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/09/">September (5)</a></li>
 130
 131 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/10/">October (7)</a></li>
 132
 133 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/11/">November (9)</a></li>
 134
 135 <li><a href="http://people.skolelinux.org/pere/blog/archive/2013/12/">December (3)</a></li>
 136
 137 </ul></li>
 138
 139 <li>2012
 140 <ul>
 141
 142 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/01/">January (7)</a></li>
 143
 144 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/02/">February (10)</a></li>
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 162 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/11/">November (10)</a></li>
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 164 <li><a href="http://people.skolelinux.org/pere/blog/archive/2012/12/">December (7)</a></li>
 165
 166 </ul></li>
 167
 168 <li>2011
 169 <ul>
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 171 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/01/">January (16)</a></li>
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 173 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/02/">February (6)</a></li>
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 191 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/11/">November (3)</a></li>
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 193 <li><a href="http://people.skolelinux.org/pere/blog/archive/2011/12/">December (1)</a></li>
 194
 195 </ul></li>
 196
 197 <li>2010
 198 <ul>
 199
 200 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/01/">January (2)</a></li>
 201
 202 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/02/">February (1)</a></li>
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 220 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/11/">November (13)</a></li>
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 222 <li><a href="http://people.skolelinux.org/pere/blog/archive/2010/12/">December (12)</a></li>
 223
 224 </ul></li>
 225
 226 <li>2009
 227 <ul>
 228
 229 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/01/">January (8)</a></li>
 230
 231 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/02/">February (8)</a></li>
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 235 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/04/">April (10)</a></li>
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 249 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/11/">November (3)</a></li>
 250
 251 <li><a href="http://people.skolelinux.org/pere/blog/archive/2009/12/">December (3)</a></li>
 252
 253 </ul></li>
 254
 255 <li>2008
 256 <ul>
 257
 258 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/11/">November (5)</a></li>
 259
 260 <li><a href="http://people.skolelinux.org/pere/blog/archive/2008/12/">December (7)</a></li>
 261
 262 </ul></li>
 263
 264 </ul>
 265
 266
 267
 268 <h2>Tags</h2>
 269 <ul>
 270
 271  <li><a href="http://people.skolelinux.org/pere/blog/tags/3d-printer">3d-printer (13)</a></li>
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