[CentOS] CentOS 6 NFS mmap I/O bug?

Tom McDonald tom at volturius.com
Mon Oct 22 18:31:45 EDT 2012


On Mon, Oct 22, 2012 at 3:15 PM, Patrick Lists
<centos-list at puzzled.xs4all.nl> wrote:
> Just a thought: could this be related to 32bit clients accessing a 64bit
> NFS server? Recently there was some discussion about this on the list.
> Iirc the solution was to use 32bit inodes on the NFS server. Search the
> list for "Mount options for NFS" posted on Oct 9. Here's a comment by
> James Person:
>
> "I would suspect the inode64 option is the problem. We had similar
> issues running 32 bit apps on a 64 bit clients accessing 'large' NFS
> servers (non-Linux NFS servers) - the 'fix' was to make sure the file
> systems were exported/mounted with 32 bit inode compatibility. I believe
> in our case the 32 bit apps in question were not compiled with large
> file support (they are/were 3rd party apps). I think if they were
> compiled with large file support, then they would work OK."

I think we have a different issue.  All the NFS clients are running
64-bit kernels and all of the code is definitely compiled to 64-bit
binaries.  The inode64 option appears to be file system mount option
used on the server side.  The two production servers in our case are
Isilon and NetApp where we don't have knobs to make this sort of
tweak.

We also actually see the problem relatively infrequently given the
number of times this operation happens, and I suspect it would happen
a lot more (especially on CentOS 4) if we were hitting a 32-bit
boundary somewhere.

Thanks for the speedy reply, Patrick!

-Tom


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