[OpenAFS] Puzzler: lack of access to AFS files

David Bear David.Bear@asu.edu
Mon, 17 Dec 2007 17:07:11 -0700

On Mon, Dec 17, 2007 at 02:28:08PM -0500, Jeffrey Altman wrote:
> The Windows Cache Manager cache is Page File backed.  If you have the
> memory, it will be loaded in RAM.
> But you are missing the point.  CIFS access is not faster than disk I/O.
>  You are creating a CIFS request, queuing it for network transfer on a
> loopback adapter, waiting for the network request to be read by the
> network stack, waiting for the SMB server code to process it, waiting
> for the request to be delivered to the AFS Client Service, waiting for
> the AFS client service to process the request and generate the response,
> waiting for the response to be queue, transfered, received, processed,
> etc. before the next request can be sent because CIFS (prior to SMB 2.0
>  in Vista) does not support chaining.
> For each file operation CIFS sends anywhere from three to five requests.
>  As a result there is significant overhead that increases the round trip
> time and limits the overall throughput.

So I take from this exchange the the surest way to improve openafs
performance for windows clients would be to convert the windows cache
manager into a true windows IFS... (i.e. get rid of the smb server
redirector and replace it with a pure openafs redirector) all other
perfmance improvements elsewhere are really ... . not worth while?

David Bear
phone: 	602-496-0424
fax: 	602-496-0955
College of Public Programs/ASU
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