Date: Tue, 17 Apr 2001 15:35:44 +0100 From: Ian Dowse <iedowse@maths.tcd.ie> To: Stijn Hoop <stijn@win.tue.nl> Cc: freebsd-stable@freebsd.org, iedowse@maths.tcd.ie Subject: Re: delayed security email? Message-ID: <200104171535.aa75540@salmon.maths.tcd.ie> In-Reply-To: Your message of "Tue, 17 Apr 2001 13:43:55 %2B0200." <20010417134355.A58593@pcwin002.win.tue.nl>
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In message <20010417134355.A58593@pcwin002.win.tue.nl>, Stijn Hoop writes: > >Now, I know for sure that I only had /usr/ports mounted during the time. >And I think it's very strange that the daily security check would fail >to mail me when a mount of /usr/ports is failing. Can anyone explain >why this would happen? I don't think the security mail should be delayed >for a reason like this. This is well-known and expected NFS behaviour. However, there are some NFS mount options that can help. By default, NFS filesystems maintain the semantics of local disks; i.e. accesses to them will never time out, and are not interruptible, so if an NFS server takes week to successfully read file, then the read operation on the client will simply take a week to complete. Obviously with local disks you rarely see delays this long :-) If the "-i" (interruptible) flags is given, then the client will still wait forever if a server doesn't respond, but you can interrupt the process if you wish. Unless you have a very good reason not to want interruptable mounts, you should always specify this to avoid unkillable hung processes while the server is down. The "-s" (soft) option is probably what you want. When specified, the client will timeout if the server has not responded within a reasonable time. Note that doing this can be bad; some applications may not be expecting a failure from a supposedly-reliable disk operation, so data loss might occur. There are also occasions where NFS can get confused, and time out a request when the server is alive, but just busy. See the mount_nfs manpage for further details. In general though, NFS only works well when the server is available at all times. You may have some success with the "amd" automounter which can unmount filesystems that are not in use, but even that can result in hung mounts when the server goes away. Ian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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