Red Hat Bugzilla – Bug 139355
Documentation for 'rsize' and 'wsize' NFS mount options is misleading
Last modified: 2007-11-30 17:07:05 EST
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Description of problem:
In the section detailing mount options for NFS filesystems, it says
that the default value for rsize and wsize options is 4k.
This will make your nfs connection faster than with the default
buffer size of 4096. (NFSv2 does not work with larger values of
rsize and wsize.)
This does not tie up with what the kernel source appears to be doing,
which is to use the server specified default values. The performance
turning pages at http://nfs.sourceforge.net/nfs-howto/performance.html
also say that the default is typically server specified.
If no rsize and wsize options are specified, the default varies by
which version of NFS we are using. The most common default is 4K
(4096 bytes), although for TCP-based mounts in 2.2 kernels, and
for all mounts beginning with 2.4 kernels, the server specifies
the default block size.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. man 'mount'
2. Search for 'rsize'/'wsize'
Expected Results: Documentation for default value of rsize/wsize
options corresponds to actual practice in kernel source.
The man page should probably also warn about potential problems with
an oversized rsize/wsize as the the above doc on nfs.sourceforge.net
If the rsize/wsize is too large the symptoms are very odd and not
100% obvious. A typical symptom is incomplete file lists when doing
ls, and no error messages, or reading files failing mysteriously
with no error messages.
Also, the mount(8) and nfs(5) man pages have conflicting statements
about the default rsize,wsize values. Mount(8) says 4K; nfs(5) says 1K.
Fixed in util-linux-2.11y-31.12
This issue is on Red Hat Engineering's list of planned work items
for the upcoming Red Hat Enterprise Linux 3.8 release. Engineering
resources have been assigned and barring unforeseen circumstances, Red
Hat intends to include this item in the 3.8 release.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.