blog/Using_bar_codes_at_a_computing_center.html

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   6     <title>Petter Reinholdtsen: Using bar codes at a computing center</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">Using bar codes at a computing center</div>
  24       <div class="date">20th February 2009</div>
  25       <div class="body"><p>At work with the University of Oslo, we have several hundred computers
  26 in our computing center.  This give us a challenge in tracking the
  27 location and cabling of the computers, when they are added, moved and
  28 removed.  Some times the location register is not updated when a
  29 computer is inserted or moved and we then have to search the room for
  30 the "missing" computer.</p>
  31
  32 <p>In the last issue of Linux Journal, I came across a project
  33 <a href="http://www.libdmtx.org/">libdmtx</a> to write and read bar
  34 code blocks as defined in the
  35 <a href="http://en.wikipedia.org/wiki/Data_Matrix">The Data Matrix
  36 Standard</a>.  This is bar codes that can be read with a normal
  37 digital camera, for example that on a cell phone, and several such bar
  38 codes can be read by libdmtx from one picture.  The bar code standard
  39 allow up to 2 KiB to be written in the tag.  There is another project
  40 with <a href="http://www.terryburton.co.uk/barcodewriter/">a bar code
  41 writer written in postscript</a> capable of creating such bar codes,
  42 but this was the first time I found a tool to read these bar
  43 codes.</p>
  44
  45 <p>It occurred to me that this could be used to tag and track the
  46 machines in our computing center.  If both racks and computers are
  47 tagged this way, we can use a picture of the rack and all its
  48 computers to detect the rack location of any computer in that rack.
  49 If we do this regularly for the entire room, we will find all
  50 locations, and can detect movements and removals.</p>
  51
  52 <p>I decided to test if this would work in practice, and picked a
  53 random rack and tagged all the machines with their names.  Next, I
  54 took pictures with my digital camera, and gave the dmtxread program
  55 these JPEG pictures to see how many tags it could read.  This worked
  56 fairly well.  If the pictures was well focused and not taken from the
  57 side, all tags in the image could be read.  Because of limited space
  58 between the racks, I was unable to get a good picture of the entire
  59 rack, but could without problem read all tags from a picture covering
  60 about half the rack.  I had to limit the search time used by dmtxread
  61 to 60000 ms to make sure it terminated in a reasonable time frame.</p>
  62
  63 <p>My conclusion is that this could work, and we should probably look
  64 at adjusting our computer tagging procedures to use bar codes for
  65 easier automatic tracking of computers.</p>
  66 </div>
  67
  68       <div class="tags">Tags: <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/nuug">nuug</a>.</div>
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