[nSLUG] cifs on Redhat Linux, and getting a full Redhat kernel for RHEL 5

George N. White III gnwiii at gmail.com
Mon May 12 19:54:27 ADT 2008

On Mon, May 12, 2008 at 4:40 PM, D G Teed <donald.teed at gmail.com> wrote:

> We've been having some fits with cifs - linux client and
>  windows server.  Files are sometimes truncated when they are not small
>  and viewed over the Linux apache server to access the files
>  mounted from Windows.

Have you looked at


>  I reproduced the problem between 2 Redhat servers, mounting with cifs,
>  and determined that any file > 256 bytes would not display.  This is
>  much worse than what I saw between Linix client and Windows server
>  with cifs mount and apache.

Have you tried the debugging support and packet sniffing?

>  Strangely, accessing the mounted files from the OS seems to be
>  without error.  It is only Apache over the mount which exhibits
>  problems.

if the files are being read from the windows servier using the same network
interface used by the apache clients, you could have a duplex mismatch, or
maybe a crappy or damaged network interface.  Try adding a
2nd network card.

>  My debian desktop can mount the Windows server with cifs
>  and serve the files in it's apache flawlessly.  It also supports
>  smbfs (which also works flawlessly), whereas Redhat has killed
>  the smbfs option in their kernel.

Smbfs is deprecated in recent kernels.   With a working debian example
you are in a good position to isolate the real cause of the problem by
comparing debugging output and packet sniffing.  I'd start by checking
software version differences and hardware differences.  Redhat tends to
provide older versions that have been heavily patched, so you may have to
look at changelogs and the sources to understand the differences.

Redhat puts a lot of effort into performance tuning for low-end hardware.
One aspect of this is making sure things work with 4k stacks, so things
are killed if a significant effort is needed to make them live in
4k stacks (e.g., SGI's xfs file system that was originally written for RISC
architecture with lots of registers).

>  I compiled a new samba on one Redhat system to test whether smbfs
>  would work better, but I'm missing the smbfs kernel module.  I put kernel-devel
>  package on there, but it does not include a full kernel.  The Redhat
>  knowledgebase
>  for Redhat 4 says you can get a full kernel with a special up2date
>  command.  'up2date' is not available in Redhat 5, and I don't find another
>  knowledgebase item describing how to get Redhat 5's full kernel.
>  Does anyone know of a resource to get the full Redhat kernel for RHEL 5?
>  Here is a tip you might want to know: purchases at Redhat's online store
>  done in error (because the description is vague) are non-refundable.

Also non-refundable if a hardware glitch prevents you from using the
software.  The clock on the support window starts ticking when the purchase is
made, so if you send off a hardware order to a major direct supplier and
they back order a part you can end up with the hardware sitting idle while
the support lapses.

>  If Redhat is not providing the kernel source they use, is this not a
>  violation of the GPL?

George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia

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