[OpenAFS-win32-devel] Windows client in Terminal server/Citrix

[Jeffrey Altman]

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Christopher D. Clausen wrote:

> I too have had this problem on Windows Terminal Servers, but have not 
> been able to track it down and it is almost always more important to get 
> the service working again than to find the problem.  And I have been 
> unable to reproduce the problem on my test systems.
> 
> I/O will just stop working into or out of AFS during file transfers and 
> there is little or no network traffic leaving the computer.  Only 
> restarting the afs client service seems to fix the problem.

I have spoken with Chris off list and I am not convinced that the issue 
he is describing is related to the one that Robin is trying to describe.

The problem Chris is seeing is with almost 99.9999% certainty the CIFS 
client disconnecting from the AFS SMB server due to fluctuations in the 
response times between its Write Data requests.  The 1.5.33 client 
addresses the issue that Chris is describing by rate limiting the 
responses to the SMB WriteData requests.  Instead of writing into the 
cache as fast as we can and sending a response back to the SMB client
we force the SMB client request to block every N bytes written where N 
is a number smaller than the maximum chunk size.  This behavior is 
controlled by the EnableSMBAsyncStore and SMBAsyncStoreSize registry 
values as documented in the Release Notes.

You can easily tell if you are experiencing the problem that Chris was 
by using the SysInternals Process Monitor to monitor all requests to 
\\AFS and drives mapped to \\AFS.  If you see the requests fail with 
"DISCONNECTED" as the response, then you know the problem is the fault 
of the Windows CIFS client breaking the connection to the AFS client 
service.  There is nothing wrong with the AFS client service, it simply 
is not responding because no requests are being sent to it.

This is the CIFS timeout problem that I have said for years can only be 
fully addressed by replacing the AFS SMB Server interface with an IFS 
Redirector kernel driver.

Jeffrey Altman

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