Date: Mon, 4 Apr 2011 16:37:20 -0300 (ADT) From: "Marc G. Fournier" <scrappy@hub.org> To: Chuck Swiger <cswiger@mac.com> Cc: freebsd-net@freebsd.org Subject: Re: 7-STABLE NFS: fatal: "select lock: Permission denied" Message-ID: <alpine.BSF.2.00.1104041632400.55888@hub.org> In-Reply-To: <DC83D7F3-260E-4718-8AF4-72F77C2980C4@mac.com> References: <alpine.BSF.2.00.1104030135160.55888@hub.org> <alpine.BSF.2.00.1104041508000.55888@hub.org> <0F56F33B-C492-4723-B7EC-713AD64E856C@mac.com> <alpine.BSF.2.00.1104041554100.55888@hub.org> <E9441056-3EFE-4668-A815-271B857FD230@mac.com> <alpine.BSF.2.00.1104041605490.55888@hub.org> <DC83D7F3-260E-4718-8AF4-72F77C2980C4@mac.com>
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On Mon, 4 Apr 2011, Chuck Swiger wrote: > On Apr 4, 2011, at 12:14 PM, Marc G. Fournier wrote: >>> OK-- Cyrus IMAP uses a variant of maildir, so you're relatively safe even if locking is not available. >> >> So, just to get this clear ... >> >> If I were to boot a diskless station using an NFS backend, then that instance would be prone to corruption since lockd wouldn't work, even though the only processes handling the files on that mount? > > If you're running a diskless system using NFS filesystem for storage, > and you run stuff that wants to do fcntl/lockf/flock locking, and > rpc.lockd isn't available, then yes, there is risk of data corruption. > However, Postfix can use .dotfile locking, even if fcntl (etc) locking > is broken, and maildir is designed to avoid needing locking the way mbox > does: > > http://www.postfix.org/NFS_README.html > > rpc.lockd provides locking at the filesystem level. Locks are performed > against file descriptors either for entire files or record-level > locking; they are not specific to a single process (indeed, locking > would be mostly useless if it was only visible within a single process). Okay, next question ... if lockd is running, should fcntl locks work? My read of the NFS_README.html above indicates to me that they should ... but if that is the case, then it comes back to why doesn't it? ---- Marc G. Fournier Hub.Org Hosting Solutions S.A. scrappy@hub.org http://www.hub.org Yahoo:yscrappy Skype: hub.org ICQ:7615664 MSN:scrappy@hub.org
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