Right, it was more of a question as to if anyone else had any problems. I figured out the errors started occurring after running powertop --auto-tune. I had the system running for maybe 12 hours, when I manually ran the command. It seems this gets them into a low power state, and they don't properly come back up (23 disks, 5 were giving read errors)? After rebooting everything is good, no powertop --auto-tune command, running for 3 days 15 hours and counting.
I will post a thread when I dare to try again, maybe someone can explain why they act the way they do. After a hike in electricity prices, I've been trying to lower the idle consumption of my server. Inspired by mgutt here and here (powertop --auto-tune).
So, with the 2 x 9207's, the whole system idles at 61-62w. No difference if try to optimize power consumption with powertop, like they wouldn't go into a lower power state. With 2 x 1166, 1 x 1064 I am at 42w (23 disks, 8 onboard sata). If I run powertop --auto-tune, the system idles at 31w. I did some tests with the 9207's I had when I was building the new system, to see how much power they consume, and it was far more power than I liked, and I couldn't get them to use less. I believe only CPU+mobo+RAM (bare system, nothing connected) 8w idle. Adding two 9207's, still no disks, total system idle at 24w.