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February 2005

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Subject:
Re: NFS server I/O blocking
From:
John Hearns <[log in to unmask]>
Reply To:
[log in to unmask]
Date:
Thu, 10 Feb 2005 15:31:44 +0000
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On Wed, 2005-02-09 at 14:02 -0500, Devin Bougie wrote:
> Hi All,
> 
> We have been struggling with what appears to be a bug in RH kernels.  
> This results in local disk I/O blocking all NFS I/O (and, as we show, 
> subsequent local I/O).  This appears easy to reproduce:
> ----
I just tried this set of steps.
Cluster, running SL 3.03,  kernel 2.4.21-27.0.1ELsmp on client and
server.

The server is a Sunfire V40z - four Opteron. The clients are a mix of
V20s and V40s.
I did tests on a V40, running as root.


Step 5, client touching a file on the NFS share when the I/O is running,
seems to take a mean of about 5 seconds.

Step 6 times are unaffected - no time increase.

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