Block Sizes

Martin Siegert siegert at
Thu Oct 31 10:07:50 PST 2002

On Thu, Oct 31, 2002 at 09:11:03AM -0800, Greg Lindahl wrote:
> On Thu, Oct 31, 2002 at 11:36:54AM -0500, Robert G. Brown wrote:
> BTW, 4K is not the pagesize on all versions of Linux; it is the
> pagesize for i386. Itanium, Alpha, sparc, sparc64, and probably others
> have larger pagesizes.
> > There are also wsize,rsizes that can be adjusted in nfs/fstab that
> > adjust how data is buffered and written back to NFS mounts.
> This is good advice; raising these to 32k often improves performance.
> However, some older Linux kernels won't raise them above 8k.

Just be careful when using NFS over udp: raising wsize,rsize to 32k
(default under RH 7.3!) will have the opposite effect: it causes (at least
non-Linux) NFS servers to become unresponsive. This is due to a bug
in the 2.4.x kernel NFS implementation that (AFAIK) will be fixed in
2.4.20, which should be out soon. Until then use NFSv3/tcp with 32k
wsize,rsize or NFS/udp with 8k wsize,rsize.


Martin Siegert
Academic Computing Services                        phone: (604) 291-4691
Simon Fraser University                            fax:   (604) 291-4242
Burnaby, British Columbia                          email: siegert at
Canada  V5A 1S6

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