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Article Data
Article Ref
2908-TIOL-4737
Written By
Thom O'Connor
Date Created
Fri, 19th Oct 2007
Updated By
Thom O'Connor
Date Modified
Thu, 8th Nov 2007
 
(Lost?)

   Linux NFS file caching bug, prior to kernel 2.6.13

Question 

What version of the Linux kernel should we be running if using a Dynamic Cluster and NFS shared file system(s)?

Answer 

Linux STABLE kernel version 2.6.13 (released August 28, 2005) fixed an NFS "file size caching" bug that some linux cluster sites (on an NFS Shared File System only) experienced. As described in more detail at the end of this message, the problem previously encountered is related only to Linux on NFS in a clustered environment.

This bug was identified during the SPECmail world-record setting tests, and CommuniGate Systems worked with some of the developers who work on the NFS client portion of the Linux kernel in order to resolve this problem. CommuniGate Systems does have a simple application test for checking for this particular problem - please contact CommuniGate Support if you feel you need this application.

There are a number of patches in 2.6.13 related to NFS, so we're not quite sure which one fixed the bug:
   http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.13

The linux 2.6.13 kernel is available here:
   http://www.kernel.org/

Anecdotally, there were reports from some customers that 2.6.14 also fixed some other potential NFS trouble spots.

Also, some Linux vendors incorporated these NFS patches into previous kernel versions, in order to proceed more cautiously in their kernel releases for their supported Linux versions. For example, RedHat has apparently backported the 2.6.12/2.6.13/2.6.14 NFS kernel patches into the RedHat ES 4.5 release, although it technically lists as "2.6.9-55.0.9.EL". For RedHat ES/AS 4.5 may be the only stable release in the RedHat 4 branch - any kernel earlier than this may likely still contain the NFS Linux kernel bugs and therefore may cause file corruption issues within the cluster.

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