This is probably no news for anyone at this point.. just wanted to share my frustration and I hope my experience will also be useful for other people who use RAID drives. I remembered Apple's screw-up with wi-fi on Yosemite, so I decided to wait for a while before upgrading to El Capitan. About a month ago I thought it's probably safe now and I upgraded to El Capitan. All seemed to be fine, until I started to use my Lacie 4TB little big disk. It would randomly disappear from the system and will or will not show up if being re-connected. Later on it just disappeared and did not want to show up at all. I googled this issue and found that if you restart El Capitan in safe mode - it will show up and it will stay there (at least for some time) if you will then restart El Capitan again and boot it normally (not in safe mode). It did work for a bit, but was irritating as hell. I decided to rebuild RAID and re-format drive - this is where I discovered that El Capitan does not support RIAD drives. It left me speechless... I had to unRAID my drives and now I am using it as two separate drives which delivers half of the RAID speed. Nice work, Apple, you keep going downhill, destroying everything I liked in you bit by bit. It is hard to understand these morons, that make these kind of decisions in Apple (like giving up RAID support), how in the hell have they got their job and manage to keep it... unbelievable.