From: s o f i a <sofiavalera@yahoo.com>
Subject: RE: Linux client network performance
Date: Thu, 26 Jun 2003 09:50:26 -0700 (PDT)
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <20030626165026.77910.qmail@web41804.mail.yahoo.com>
References: <482A3FA0050D21419C269D13989C6113127E5C@lavender-fe.eng.netapp.com>
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To: nfs@lists.sourceforge.net
In-Reply-To: <482A3FA0050D21419C269D13989C6113127E5C@lavender-fe.eng.netapp.com>
Errors-To: nfs-admin@lists.sourceforge.net

Charles thank you so much for
your pointers.  I have downloaded
the Netapp paper, and will review
it....

> that's not a very clear description of the problem.
> it sounds like your client is retransmitting NFS
> write operations, but there isn't enough in your
> description to determine why that might occur.

yes you are right, and apologize for the
vague characterization ... the issue is actually:

I have an application that performs an "NFS-copy"
on an NFS Linux client.  This Linux client is
mounted to *source* volume in a Netapp Filer; 
copying files to an NFS mounted volume on a
*destination* host: SUN Solaris 8, VERITAS Foundation
Suite. both have GigE network adapters.
The application's data movement is NFS over UDP.

The symptom I saw was that, at about 30-50%
completion of the operation, we do see the client
retransmitting NFS write operations.  In fact,
in running tcpdump on the linux client and snoop
on the Solaris host, I saw the following sequence:

- NFS write attempt from client
- is received in destination
- NFS 2nd write attempt from client
- is received in destination
- destination sends back a reply
- NFS transaction completed.
... note: the host replies to the FIRST
NFS write_attempt, not the SECOND... therefore
based on timestamps.

any thoughts or comments will be most welcome.

thank you again,

 - s o f i a

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