Dark data is information companies keep but never use—about 55% of stored data...

https://papa-wiki.win/index.php/NAS_vs_Object_Storage_for_Archives_%E2%80%93_What_Is_Cheaper_Long_Term%3F

Dark data is information companies keep but never use—about 55% of stored data goes untouched. This inactive data adds up to a $2.5 million waste on storage and increases security risks