I currently save my collection across 25 external HDDs. All of my HDDs all range from 5TB to 8TB. It's all organized in alphabetical order based on actress name. I have roughly 36TB reserved for the girls I would consider my favorites. It changes every few months but currently, there is 125 girls in said externals. I have an excel workbook to track all my movies with the movie ID, title name in Japanese and English all translated by myself since most English titles are just dumped into Google Translate which is inaccurate, file size of a movie which can range from less than 1GB to 36GB, a queue list of torrents (~2000 torrents), and a dashboard to say which HDD has said movie.
At this point, I have roughly 140TB which is about 12.5K movies. I only download THD quality movies and if that's not available, the highest quality available which is usually 5GB per movie.