title: Seek time vs Sequential read
body: <p>Let's assume that on a hard drive I have some very large data file of a sequence of characters:</p>
  
  <blockquote>
    <p>ABRDZ....</p>
  </blockquote>
  
  <p>My question is as follows, if the head is positioned at the beginning of the file, and I need  5 characters every 1000 positions interval, would it better be to do a Seek (since I know where to look) or simply have a large buffer that just reads sequentially then do job in memory.</p>
  
  <p>Naively I'd have answered that reading 'A' then seek to read 'V' is faster than >> reading all the file until ,say, position 200 (the position of 'V'). Ok, this is just an example, since smallest I/O is 512bytes. </p>
  
  <p>Edit: my previous self-naive-answer is partly justified by the following case: given a 100Gb file I need the first and the last charcters; Here I obviously would do a seek .... right?</p>
  
  <p>Maybe there is a trade off between how "long" is the seek vs how much data to retrieve?</p>
  
  <p>Can someone clarify this to me?</p>