Date: Mon, 21 Sep 2009 12:20:56 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: "M. Warner Losh" <imp@bsdimp.com> Cc: svn-src-head@FreeBSD.org, rmacklem@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, jhb@FreeBSD.org Subject: Re: svn commit: r197298 - head/sbin/mount_nfs Message-ID: <Pine.GSO.4.63.0909211204590.7436@muncher.cs.uoguelph.ca> In-Reply-To: <20090920.155347.-675685342.imp@bsdimp.com> References: <4AB495DD.1010006@FreeBSD.org> <20090919.230053.58383965.imp@bsdimp.com> <Pine.GSO.4.63.0909201722330.22125@muncher.cs.uoguelph.ca> <20090920.155347.-675685342.imp@bsdimp.com>
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On Sun, 20 Sep 2009, M. Warner Losh wrote: > : Someone mentioned an issue w.r.t. umount using UDP, which was basically > : a slow timeout when a server didn't handle the UDP call, such as when > : it was down. I'd guess that a TCP attempt would fail more quickly than > : a UDP attempt when the server doesn't have rpcbind/portmapper running. > : (Not so sure when the server has crashed, but I'm guessing that the TCP > : connection attempt fails more quickly than the N retries over UDP?) > > A server down would have the same timeout issues as a UDP timeout. > I was thinking of this email: http://docs.freebsd.org/cgi/getmsg.cgi?fetch=213665+0+archive/2009/freebsd-current/2 Actually, we were both wrong (although you were closer), at least for the little experiment I just tried.:-) When the server is up, but not supporting that protocol (UDP or TCP), both cases failed in < 1sec. (So, you got this one right. I had thought UDP would take longer, but it didn't. It appears that the ICMP Dest Unreachable causes it to fail quickly. I have no idea if ICMP Dest. Unreachable messages get forwarded normally. Maybe that's what the email was alluding to when he said "some situations".) When the server is down/network partitioned, it actually took longer for TCP (1min vs about 10sec) for the defaults in the 8.0 RPC libraries. Probably not relevent to the discussion, but I thought someone might find it interesting, rick
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