[OpenAFS] Puzzler: lack of access to AFS files

Rodney M. Dyer rmdyer@uncc.edu
Mon, 17 Dec 2007 13:43:26 -0500

At 10:46 AM 12/17/2007, Jeffrey Altman wrote:
>While AFS on UNIX is limited by the performance of Rx/UDP, on Windows we 
>are actually limited by the CIFS/SMB implementation.  A native redirector 
>will be a big win here.

Am I wrong here in thinking that the code for CIFS/SMB access is already 
faster than network + raw disk read access, and that any more improvements 
are simply ram cache read related improvements?  I mean a 7200 rpm disk can 
only spin so fast, and these disks don't have 100 MB ram caches.  Once 
you've read out 8-16 MB of the file, your basically waiting on the disk.

On a related note, I've always wondered why the AFS file servers do not 
have "read cache" on the server side, so when one person requests a file, 
the second person sees the same file from the servers cache.  Or is that 
handled by the server OS cache (via the swap)?

>Rodney's complaint about reliability was not about the file servers but 
>about the clients.

How do I know?  If I request a 100 MB file from the file server and get the 
following error on random machines at random times...

    From the Visual Studio 2005 install log:

      "Error 1335.The cabinet file
      required for this installation is corrupt and cannot be
      used. This could indicate a network error, an error
      reading from the CD-ROM, or a problem with this

... then how do I know where the problem lies?  This is similar to other 
application install errors that we get from time to time.

>   If a user can't save their work from the application they are using and 
> the application crashes as a result, then the AFS client is unreliable.

In the above instance, the AFS client/server environment can cause us grief 
as IT administrators in performing change-management of our PC client 
software.  To debug issues like this can take hours.  That's a lot of money 
and productivity down the tubes.

I'm willing to put up with issues like this because of my "expectations", 
however new adopters to the AFS world are not.  This is why I'm sometimes 
reluctant to advocate AFS at times.