@martindunajsky - Just to be clear here you need to pull both drives as the set is the Fusion Drive.
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Can you explain a bit more about this system use. Is this static work Art/Photo pieces or Vids. Are you rendering or running a slide show or video loop type of presentation?
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This gets into the data churn the drive gets. Don’t forget the drive also offers Virtual RAM and caching and some Apps use scratch space as well.