Backing them up on MDISC DVDs or Blu-Rays is doable. 6 CDs per DVD if you want to store them bit-by-bit. 12 CDs if you go for losless compression. Around 35 CDs

Backing them up on MDISC DVDs or Blu-Rays is doable. 6 CDs per DVD if you want to store them bit-by-bit. 12 CDs if you go for losless compression. Around 35 CDs per DVD if you do 256kbit/s MP3 or something like that. MDISC are supposed to last for 100 years or so.