[OpenAFS] Tuning openafs write speed

[Robert Banz]

> memcache is much faster than the disk cache.  memcache will not get  
> any
> better if no one ever uses it so the openafs developers can get some
> bug reports.  i think memcache has improved quite a bit (but it could
> be better, i need to submit some patches) over the last couple years.
>
> i use '-memcache -chunksize 15 -dcache 1024'.  if your system is  
> memory
> starved this might be an issue.

I did a whole bunch of testing regarding cache performances while  
we've been moving all of our users off of AFS-hosted mailspools, and  
here's what I've found -- this is on Sol 10 x86...

* slowest: disk cache, of course.
* medium: memory cache
* fastest: ufs filesystem on a lofi-mounted "block device" hosted in / 
tmp  (which is in-RAM)
	(I know this certainly wastes some cpu/memory resources and  
overhead, but...  it works)