I've searched the web as well as these forums and can't find an instance of my exact scenario. My apologies if somehow this was asked before by someone else. I am still running Yosemite, but finally have a break between projects where I am able to make the jump to Sierra. I have an external Lacie 5big Thunderbolt (spec 1) 20TB RAID that has a lot of project data on it that I want to leave intact & unchanged. The bulk of this "data" are video source files as well as project files (i.e. Premiere, Avid, DaVinci Resolve project files). I have automated backups of my project files in place, as well as redundant backups of the video source files on bare SATA hard drives. So yes, I do have backups- but were I to have my raid unexpectedly wiped out- it would still be a major pain to rebuild everything. The Question: Can I upgrade to Sierra from Yosemite without having to reformat my raid drive? I know raid configuration was removed from El Capitan and re-instated in Sierra, but I have no idea of what other ramifications may be, if any. Thanks in advance.