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   5   <title>Petter Reinholdtsen: Using bar codes at a computing center</title>
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  12        <a href="http://people.skolelinux.org/pere/blog/">Petter Reinholdtsen</a>
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  20   <div class="title">Using bar codes at a computing center</div>
  21   <div class="date">2009-02-20 08:50</div>
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  23 <p>At work with the University of Oslo, we have several hundred computers
  24 in our computing center.  This give us a challenge in tracking the
  25 location and cabling of the computers, when they are added, moved and
  26 removed.  Some times the location register is not updated when a
  27 computer is inserted or moved and we then have to search the room for
  28 the "missing" computer.</p>
  29
  30 <p>In the last issue of Linux Journal, I came across a project
  31 <a href="http://www.libdmtx.org/">libdmtx</a> to write and read bar
  32 code blocks as defined in the
  33 <a href="http://en.wikipedia.org/wiki/Data_Matrix">The Data Matrix
  34 Standard</a>.  This is bar codes that can be read with a normal
  35 digital camera, for example that on a cell phone, and several such bar
  36 codes can be read by libdmtx from one picture.  The bar code standard
  37 allow up to 2 KiB to be written in the tag.  There is another project
  38 with <a href="http://www.terryburton.co.uk/barcodewriter/">a bar code
  39 writer written in postscript</a> capable of creating such bar codes,
  40 but this was the first time I found a tool to read these bar
  41 codes.</p>
  42
  43 <p>It occurred to me that this could be used to tag and track the
  44 machines in our computing center.  If both racks and computers are
  45 tagged this way, we can use a picture of the rack and all its
  46 computers to detect the rack location of any computer in that rack.
  47 If we do this regularly for the entire room, we will find all
  48 locations, and can detect movements and removals.</p>
  49
  50 <p>I decided to test if this would work in practice, and picked a
  51 random rack and tagged all the machines with their names.  Next, I
  52 took pictures with my digital camera, and gave the dmtxread program
  53 these JPEG pictures to see how many tags it could read.  This worked
  54 fairly well.  If the pictures was well focused and not taken from the
  55 side, all tags in the image could be read.  Because of limited space
  56 between the racks, I was unable to get a good picture of the entire
  57 rack, but could without problem read all tags from a picture covering
  58 about half the rack.  I had to limit the search time used by dmtxread
  59 to 60000 ms to make sure it terminated in a reasonable time frame.</p>
  60
  61 <p>My conclusion is that this could work, and we should probably look
  62 at adjusting our computer tagging procedures to use bar codes for
  63 easier automatic tracking of computers.</p>
  64 </div>
  65
  66   <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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