md devices mounted with async

[Wojciech Puchar]

>
> mdmfs(8) has an example of a malloc-backed md device mounted with the
> async option. Is there any point in doing this with malloc and vnode
> devices? In neither case does a write to the file-system require a write
> to a physical disk.
i don't think so.

but if you use FreeBSD 7 use tmpfs. it says it's experimental feature, but 
still not crashed on 3 computers i use it.

what it's missing is some kind of quota, you may crash the system by 
simply filling it up and using all swap