[OpenAFS] Serving Windows Media Files

Jason Simons jason.simons@duke.edu
Wed, 25 Apr 2007 11:38:13 -0400

We would like to use OpenAFS as storage to serve Windows Media Files  
for steaming through 64bit Windows 2003 R2's Windows Media Services.   
We understand that streaming performance will always be better on  
local storage, but we were hoping to get decent performance using  
OpenAFS but so far we haven't been successful.  When we run load  
tests on the server using Microsoft's Windows Media Load Analyzer, we  
are able to consitently get around 350 simultaneous connections  
without error using local storage depending on the file's bitrate  
(average is 500 kbps).  Using the same files on AFS, we can barely  
get 150 connections without error.  We also noticed that when a file  
is added to AFS and we try to stream it, the first time it is used  
the performance is very bad.  Subsequent attempts yield better  
result.  My guess is that this is a caching issue.

Right now I have the OpenAFS 64 bit client version 1-5-18 installed  
on the server.  I increased the default Cache Size to 2GB which  
changed the Status Cache to 262144 entries.  The Chunk size is at the  
default 128kb.  I was wondering if there are recommendations for  
optimizing the client for better performance?  Any help would be  
greatly appreciated!