I don't think very few (if any) Jews,Gays,Disabled or Gypsies new what was awaiting them in the Concentration Camps.
Some had heard of these camps,but even those that did thought they were (as they were told) just "work Camps" where they would be "safe" from the agressive nature of the Non Jews/Gays/Disabled/Gypsies.
Indeed many Germans (at the start) thought that too.It was to begin with only the people that lived near the camps that new the awful things that went on there.It only started to filter out into the general population as the war progressed,but people looked away and thought "The Fuhrer must know what he is doing,and there must be a reason for it"
When the war ended and the scale of the slaughter was revealed some (brave) Germans admitted to it,but many denied what had happened or just ignored it altogether.
There are STILL older Germans who say the Holcaust was an American (Jewish) invention,hence the law in Germany making denial of the Holcaust illegal.
My Wife's Mother was Jewish,and she and my wife survived the camps,but most of her family did not.
She was completely unaware of just what lay instore for her in them.
My wife and I married (in Germany) in 1948,and I brought her back to the UK.She did experience some prejudice,but after the camps it was a holiday to her!