Subject: Re: Default NFS write size?
To: Andrew Gillham <>
From: Greywolf <>
List: current-users
Date: 05/14/2002 23:56:30
On Tue, 14 May 2002, Andrew Gillham wrote:

# On Tue, May 14, 2002 at 04:59:04PM -0700, Greywolf wrote:
# > much moaning and wailing and gnashing of teeth), and I found that specifying
# > -w=8192 fixes the problem.
# Does this happen with any size of write, or just large (over 8K) writes?

Seems to have been large writes, as I was able to manipulate small

# Have you tried TCP mounts instead of UDP?

I use TCP.  They're both NetBSD boxen...

# My guess is that your 100Mbit/s box + switch combo is sending too many
# packets back to back and your Sparc is choking.  Your 100Mbit/s box keeps
# trying the same UDP write and it can never complete.

I should have included a tcpdump, probably, but my user/kernel are a bit
out of date.  Enough so that tcpdump was producing a very large unsigned
32-bit value as a source port.  I don't *think* this is supposed to
happen that way.  It would try to write the frags and just hang.

# Also, I've stumbled across a problem with ~recent -current where AMD mounts
# hang in vnlock.  I haven't had much time to troubleshoot the problem yet.
# It sounds a lot like your issue though now that I think more about it.

I don't use AMD, so your problem is probably not AMD.  I *do*, however,
have /var/run and /tmp mounted mfs.  I've had to mangle my rc.d set so
that just about everything that gets started has a shutdown keyword, or
else the system hangs dead with about a dozen processes trapped in

# Most of these super cheap switches are based on the same chips.  e.g. It
# may be a realtek or VIA, etc.  They are all usually store&forward, so you
# should not typically see any kind of packet mangling being done by the
# switch.  But... If you have crappy cabling, mismatched duplex, or bad NICs
# you will have plenty of issues. :-)

Hmmmm.  I can't vouch for the cabling; rebooting should have fixed it if
duplex was the issue, and the hardware's been rock solid for months.

# -Andrew


[I gotta make it down to the BANUG again.]

NetBSD: the second best thing you can get for free.