Jason Simons wrote:
> 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!
> 
> Jason

You won't be able to serve faster than you can read from the AFS file
server on the first request.  Subsequent requests will go faster
provided they are resident in the cache.   However, you will still be
limited by the CIFS/SMB gateway limitations.  You can't have more than
63 simultaneous CIFS requests being served.

When there is a native file system client instead of a CIFS/SMB gateway
client for AFS on Windows, then you will be able to serve data as fast
as you can read it out of the cache.  In order to make that happen we
require resources == money.

Btw, OAFW on 64-bit Windows should be able to handle much larger cache
sizes.

Jeffrey Altman
Secure Endpoints Inc.



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