There is one more feature that zram can do: multiple compression levels. I use simple bash script to first use fast compression and after 1h recompress it using much stronger compression.

unfortunately you cannot chain it with any additional layer or offload to disk later on, because recompression breaks idle tracking by setting timestamp to 0 (so it's 1970 again)

https://gist.github.com/Szpadel/9a1960e52121e798a240a9b320ec...