5 Comments on “What is the usable disk space of a RAID 5 array of five 18GB drives with one drive dedicated as a spare?”

1. ano says:

   August 16, 2016 at 10:52 am

   C.
   RAID5 uses one disk for Parity and requires at least three drives to be used.
   3*18GB=54GB

   
   
   
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   1. Popbi says:

      March 5, 2017 at 9:35 pm

      The question asked “RAID 5 array of five 18GB drives”
      5 * 18 = 90GB

      
      
      
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2. zz says:

   September 25, 2017 at 4:35 pm

   question is about usable space, you have 5 disks, one for spare and one for parity
   5-1-1=3 drives
   3*18GB=54GB
   54GB is a good answer

   
   
   
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3. Skep says:

   November 16, 2017 at 8:10 am

   Isn’t there only one disk needed for parity? Means, only one of five disks does not count as disk space?

   
   
   
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   1. JoeBlack says:

      April 16, 2018 at 5:19 am

      One disk is used as “spare” …. therefor does not count either.

      
      
      
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