Date: Fri, 4 Jul 2014 17:20:47 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: kpneal@pobox.com Cc: Marc Fournier <scrappy@hub.org>, freebsd-stable@freebsd.org Subject: Re: FreeBSD 10.x + LiquidSoap + NFS == Server Hang Message-ID: <1127183499.7467557.1404508847886.JavaMail.root@uoguelph.ca> In-Reply-To: <20140704175251.GB62030@neutralgood.org>
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Kevin P. Neal wrote:
> On Fri, Jul 04, 2014 at 09:33:48AM -0700, Marc Fournier wrote:
> > I=E2=80=99ve made the change on two of my servers that have been exhibi=
ting
> > NFS related issues, so we=E2=80=99ll see how this goes over the next
> > couple of days, but am curious as to when one would use =E2=80=98intr=
=E2=80=99 in
> > the first place, if by using it, it could cause NFS to hang like
> > this? Granted, out of 11 servers using =E2=80=98intr=E2=80=99, this on=
e server is
> > the only one that I=E2=80=99ve knowingly experienced the nfs_getpages, =
so
> > it seems to be something hard to trigger =E2=80=A6
>=20
> It used to be that if you had an nfs mount that was nointr, and the
> server
> died, then any client programs that were in the middle of an I/O
> would
> hang forever.
Well, until the server comes back up, actually.
There is no perfect solution, but I always used hard mounts (no intr, soft)
and just tried to make sure my NFS servers were reliable (same w.r.t. netwo=
rk
fabric), when I wore a sysadmin hat.
There is "umount -f", which can get rid of a hung server. Unfortunately, if
you do a "umount" (without -f) that is stuck on the crashed server's mount
point, "umount -f" won't work, because the other "umount" will have the mou=
nt
point locked up.
rick
ps: Both John Baldwin and Kostik have made changes to how certain signals a=
re
handled during syscalls (and also what happens when an nfs_getpages() f=
ails)
so the behaviour is dependent upon FreeBSD version.
> --
> Kevin P. Neal
> http://www.pobox.com/~kpn/
> "Oh, I've heard that paradox a couple of times, but there's something
> about a cat dying and I hate to think of such things."
> - Dr. Donald Knuth speaking of Schrodinger's cat, December 8, 1999,
> MIT
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