So, I bought three 3TB drives and made a RAID5 with them, despite numerous advices against it (there is even a society called BAARF - Battle Against Any RAID Four/Five).
But, of course, I just had to see it for myself...
With the "fake" onboard RAID controller (Intel ICH10R), I did not expect any stellar results. But the reality was even worse than I expected.
First of all, it took two days
to initialize the RAID.
You can use the arrays before and during initialization, but the performance would be really abysmal. So what did I get after the long wait was over?
Sequential read speed: down 27%
compared to a standalone disk.
Sequential write speed: down 44%
512K block read speed: down 32%
512K block write speed: down 88%
4K block read speed: up 4%
. Probably just a statistical deviation.
4K block write speed: down 12%
4K block read with queue depth 32: up 125%
4K block write with queue depth 32: down 8%
I think I should go buy one more drive and make a RAID10.