Can we trust fsync?

I'm really concerned by this post on Linux's fsync and disk flush behaviour:

http://milek.blogspot.com.au/2010/12/linux-osync-and-write-barriers.html

and seeking opinions from folks here who've been deeply involved in
write reliability work.

The amount of change in write reliablity behaviour in Linux across
kernel versions, file systems and storage abstraction layers is worrying
- different results for LVM vs !LVM, md vs !md, ext3 vs other, etc.

If this isn't something that's already been seen and dealt with then
I'll see if I can take a look into it once the RLS work is dealt with.

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services