[OpenAFS] Fair bandwidth distribution, performance of OpenAFS on win32

[Matthias Gerstner]

Hello everybody,

I have a question regarding bandwidth (or more general: ressource)
allocation in an OpenAFS setup. I'm maintaining a small installation
with one server and a dozen of clients. Server and most clients run on
Linux. Some clients also on MS Windows 7. Authentication is done by way
of MS Server 2008 AD.

The problem I have is that time and again a user needs to perform rather
performace killing operations on AFS. That is compiling a large software
project with accessing a large number of small files and also producing
a large number of files.

In this situation other users with moderate load on AFS suffer a bad
user experience. That is not necessarily that absolute bandwidth is too
low. It is rather that interactive work becomes annoying as operations
on AFS tend to block repeatedly. For example writing a small text file
can takes up to five seconds until suddenly everything goes back to
normal.

I wonder what would be the best approach to improve the user experience
for such cases. A low-level approach like extensions to the TCP/IP stack
on the Linux server machine might be one example. But I feel that given
the complexity of OpenAFS this is probably not the route to take. So I
thought maybe using the distribution properties of OpenAFS might be a
better way. Are there any best practices for such a scenario?

On a different matter I experience that running the OpenAFS client on
MS Windows turns out generally really, *really* slow. From my knowledge
MS Windows simply isn't very good regarding file operations even on
local disks in comparison to UNIX systems. But working with OpenAFS on
MS Windows is even worse than the usual. When comparing the performance
between the Windows and the Linux OpenAFS clients I'm at least four
times slower on Windows than on Linux. This can also be experienced
during interactive work with the Windows client when operating on AFS.
Question is if this is a known fact. Or if not so what I could do to
relieve the problem.

Any help is appreciated,

Matthias

-- 
Matthias Gerstner, Dipl.-Wirtsch.-Inf. (FH), Senior Software Engineer
e.solutions GmbH

Am Wolfsmantel 46, 91058 Erlangen, Germany

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