From owner-freebsd-cluster Wed Dec 11 17:27:25 2002 Delivered-To: freebsd-cluster@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CD6EA37B401 for ; Wed, 11 Dec 2002 17:27:23 -0800 (PST) Received: from malasada.lava.net (malasada.lava.net [64.65.64.17]) by mx1.FreeBSD.org (Postfix) with ESMTP id 42A5843EA9 for ; Wed, 11 Dec 2002 17:27:23 -0800 (PST) (envelope-from cliftonr@lava.net) Received: from localhost (3547 bytes) by malasada.lava.net; Wed, 11 Dec 2002 15:27:14 -1000 (HST) via sendmail [stdio] id for Date: Wed, 11 Dec 2002 15:27:14 -1000 From: Clifton Royston To: "Ronald G. Minnich" Cc: Joshua Goodall , Michael Grant , freebsd-cluster@FreeBSD.ORG Subject: Re: sharing files within a cluster Message-ID: <20021211152714.A25854@lava.net> Mail-Followup-To: "Ronald G. Minnich" , Joshua Goodall , Michael Grant , freebsd-cluster@FreeBSD.ORG References: <20021210222210.GG98967@roughtrade.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from rminnich@lanl.gov on Tue, Dec 10, 2002 at 03:30:55PM -0700 Sender: owner-freebsd-cluster@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Tue, Dec 10, 2002 at 03:30:55PM -0700, Ronald G. Minnich wrote: > On Wed, 11 Dec 2002, Joshua Goodall wrote: > > > * NFS probably is robust enough for some environments. A suggestion > > I was given to remember with cross-mounts is to use soft/interruptible, and The most critical thing with NFS cross-mounts is that all servers involved need to have their boot sequences carefully checked for dependencies, and preferably should have two separate phases - one which gets the servers up to the point that they can act reliably as a *server* for all NFS volumes they export, and only start trying to mount NFS volumes from other servers after the first phase is completed successfully, If you make a mistake in this - or if your default rc scripts do - you can end up configuring a situation where your entire network is unbootable if more than one server goes down, because you have NFS volumes listed in multiple servers' fstabs, and the servers then deadlock trying to mount each other at startup. (This happened to me some years back at a previous job where a lot of random cross-mounts were set up on various HP-UX servers.) > > always login as root directly (rather than trying to sudo from a user > > account that may have just become unavailable in /home). > > soft/interruptible: bad. Leads to large blocks of zeros in files. Interruptible is quite different from soft. Soft = bad ("emulates a broken hard drive".) Interruptible = GOOD! (avoids creating processes that are effectively unkillable until the NFS server comes back up.) Note that this doesn't lead to misread/miswritten files, unless that could normally result from a process being killed with an interrupt signal. man mount_nfs ... -i Make the mount interruptible, which implies that file system calls that are delayed due to an unresponsive server will fail with EINTR when a termination signal is posted for the process. ... > Spongy: > better. I've seen this referred to, but had not seen a system that actually implements spongy NFS mounts. Does FreeBSD-stable or -current actually support spongy mounts? Have I missed this in the docs? -- Clifton -- Clifton Royston -- LavaNet Systems Architect -- cliftonr@lava.net "If you ride fast enough, the Specialist can't catch you." "What's the Specialist?" Samantha says. "The Specialist wears a hat," says the babysitter. "The hat makes noises." She doesn't say anything else. Kelly Link, _The Specialist's Hat_ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-cluster" in the body of the message