> I think there is only one solution to prevent file system damage: Make
> sure that power will not fail, never.

Power can and will fail.  Even with a UPS.  :-(

> This is also the reason why "good"
> hardware RAID systems have a NV write cache... Not to talk about the
> on-disk write back cache... Especially the later can make it really hard
> to guarantee data integrity. Even for FFS1 and softdeps. (AFAIK)

In reading this thread, it sounds like FFS is the preferred FS for avoiding
data loss on *BSD.  I only recall losing data once in many years with
NetBSD's FFS, a great improvement over previous BSD based systems.

If one is forced to run Linux :-( which FS is the least likely
to lose data, and how much worse is it than NetBSD's FFS?