From owner-freebsd-net@FreeBSD.ORG Tue Apr 5 08:11:49 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6C3B11065670 for ; Tue, 5 Apr 2011 08:11:49 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) by mx1.freebsd.org (Postfix) with ESMTP id 2F2EE8FC18 for ; Tue, 5 Apr 2011 08:11:49 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id p358Bj5C040467 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 5 Apr 2011 01:11:47 -0700 (PDT) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id p358BjMg040466; Tue, 5 Apr 2011 01:11:45 -0700 (PDT) Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA26744; Tue, 5 Apr 11 01:01:50 PDT Date: Tue, 05 Apr 2011 01:01:23 -0700 From: perryh@pluto.rain.com To: cswiger@mac.com Message-Id: <4d9acc53.w52H7UX61+6sZ3rH%perryh@pluto.rain.com> References: <1359778820.2757108.1301963093210.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: scrappy@hub.org, freebsd-net@freebsd.org, rmacklem@uoguelph.ca Subject: Re: 7-STABLE NFS: fatal: "select lock: Permission denied" X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Apr 2011 08:11:49 -0000 Chuck Swiger wrote: > It's fairly common to scale up a mail infrastructure from one box > handling both SMTP and IMAP (or POP) to a SMTP-only box writing to > NFS-mounted user mailboxes, and have one or more dedicated reader > boxes which only run IMAP/POP daemons which access that same NFS > filesystem holding the user mailboxes. Yikes! The _proper_ way to scale up from one box to multiple goes something like this: SMTP Internet ---> mail. [original box] This box now runs only the SMTP receiver, and perhaps the spam/virus filtering (if it has enough capacity). It contains no user mailboxes. SMTP mail. --+--> mailbox01. | This box runs local delivery, and IMAP/POP | daemons, for some user mailboxes (which are | stored on _local_ disks). It may also handle | spam/virus filtering for those mailboxes, if | mail. can't handle that load. | +--> mailbox02. | This box is just like mailbox01, for a different | set of user mailboxes. | +--> mailbox03. etc. -- as many as needed. mail. becomes a multiplexer, so that the outside world can send to @mail. (or simply @ if you prefer) without needing to know about the internal structure. The multiplexing can be very simple, and thus very fast, by doing a table-lookup based on the first character of . There's no need for NFS anywhere in the setup. > ... I've been burned by NFS locking (mis)adventures in the past, > and I hate to see people depend on it if they have alternatives.... As have I. Once. That was enough.