The files on CDs are aligned to 2 kB boundaries. Dedup is looking for n kB continuous block. If the block size of the material you want to dedup does not match to the block size of dedup system, you&#x27;ll get suboptimal results. The bigger the difference, the worse the results.<p>Say you have this data:<p><pre><code>  ABCABCBACCBBABCC
</code></pre>
Dedup system that has block size of 1 can see you really have just three unique blocks, A, B and C.<p>Same data, but dedup with block size of 2:<p><pre><code>  AB CA BC BA CC BB AB CC
</code></pre>
Dedup block size of 2 thinks you have 6 unique blocks: AB, CA, BC, BA, CC and BB.<p>Etc.