Filesystem corruption when drives are mirrored, but not otherwise

[Dieter]

> It seems that this was caused by the (infamous) problem when
> softupdates and write caching are both enabled. Disabling write
> caching seems to have fixed the problem.

Interesting.  The disk write cache being on should only cause
problems if the system goes down hard/unclean, e.g. power failure.
Unless the disk firmware has a bug?  Anyway the disk write cache
should be off, since even a UPS can't guarantee that the system
will not go down hard.

> Unfortunately the disk write performance is woeful. There must
> be a  better way surely?

I think that getting NCQ support would help greatly.

There are also problems like the one with nforce4 and
some brands of disks:
http://forums.nvidia.com/lofiversion/index.php?t8171.html

It is not obvious what any of this would have to do with mirroring vs.
not mirroring.