This is a question that should be easy to answer, but not so obvious.
From  it seems that disabling the hard disks write cache is a
requirement to increase the fast filesystem reliability in NetBSD. I asked
some related questions in the past; now I am interested in know:
1. if we should disable the write cache in hard disk drives that
support this feature; and,
2. if we should disable the read look-ahead option too.
(I believe that the answer to the first question will be "yes", but
the answer to the second one will be "no" or "it does not matters".)
Any advice will be highly appreciated.
 Gregory R. Ganger, Marshall Kirk McKusick, Craig A. N. Soules,
Yale N. Patt. Soft updates: a solution to the metadata update problem
in file systems, ACM Transactions on Computer Systems 18(2), May 2000.