NFS defaults for read/write blocksize....(Was: Re: 5.4/amd64 console hang)

Claus Guttesen kometen at
Mon Apr 18 13:53:30 PDT 2005

> >>>>By the way, I'm thinking that more frequently hang might related with
> >>>>large read/write block in mount_nfs -r/-w (I use 8192, original is 1024).
> >>Has it even been considered to up these values to something bigger??
> > Read- and write-size of 32768 seems to work optimal for me:
> How did you come to this conclusion? What kind of workload?

To make a short story long ;-)

Last year just after christmas I got a new storage system and had an
opportunity to replace our Linux-nfs-server with FreeBSD. I searched
the archives for nfs-related tuning-information, and found some links
suggesting the usage of tcp rather than udp and adjusting the
r/w-size. So I nfs-mounted some clients and started to copy back and
forth. The december release of the (back then) current had some
"server not responding" messages, but they appeared less with
r/w-sizes of 32768. The copying itself was faster as well.

So I upgraded (two or three times) until I had the Feb. 18'th 2004
current and the "server not responding" almost vanished. Some weeks
after that the server went into production and have been rock-stable!
It went down once but that was only due to a poweroutage that lasted a
few hours, longest uptime was 117 days before I took it down for

The files are at most some MB in size (images) and some KB (thumbnails).

> This is in line with what the graphs suggest:
>         Use Laaarrrrrggggeee sizes.

And use tcp as well.


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