I would like to say what I did, and hopefully someone could tell me how I messed this up, because I'm sure I've horked this thing real good.
I started with an old HP All-In-One I had that was already running Debian, so I installed OMV 3.0.59 on it, along with 2 3TB Seagate USB drives, which I told OMV to link together as RAID 5. It took about 4 days, but it worked. This has been my NAS for the last few months. About 2 months ago, I decided to get serious about allowing my Roku and PS3 to start streaming from my NAS again (old solution was GoFlex Home; bad choice, because all movies had to either be in MP4, or 2 other formats to be played, since PS3 won't play MKV, etc), since I saw that PLEX might be a good solution to stream to both. So, installed PLEX Server as a plug-in on the OMV install on the HP. Worked great until last week.
All of a sudden, last week, even though my Roku and PS3 and both wired to my network, neither can stream very well. Both were having trouble with 320p. So, I moved the server to another box, but the server wasn't the problem; it was the HP having issues. I decided to get a Raspberry Pi and move everything there.
So, without asking questions, I just forged ahead (like the ID10T that I am), got the RPi3, installed OMV3 (which worked flawlessly), then followed this guide in the forum, not even thinking twice that it might not fit my particular situation.
When I restarted my RPi3, the dashboard would come up ok, but when I would click on File System, it would give me an unspecified "communication failure" over and over. Closing the window and logging in again would show the dashboard again, but this time, the CPU usage was at 100%, and stayed there for over 2 days, with the Load Average climbing and climbing until it hit 130, 130, 130. It finally backed down, and the "communication failure" pop-ups are at a minimal now, except for when I click on the File Systems link. Then, that's all I get, even if I successfully go somewhere else, like Physical Disks.
Now, I haven't turned the HP back on since I unplugged the USB drives. I might try to turn off the RPi3 and plug those drives back into the HP, turn it on, and see if it can still recognize the RAID 5. Otherwise, it looks like I might have to wipe both disks and start over.
Is there something I could've done to avoid this? What happens in the future when I want to expand? I just planned on buying a powered USB hub, plugging these drives into that, and two other drives next to those. Will this thing flip out if I do that?
I guess I should probably plan these things better. And sorry for the long post.