From owner-freebsd-stable@FreeBSD.ORG Mon Oct 27 19:10:33 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 35D5C106567A for ; Mon, 27 Oct 2008 19:10:33 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from QMTA08.westchester.pa.mail.comcast.net (qmta08.westchester.pa.mail.comcast.net [76.96.62.80]) by mx1.freebsd.org (Postfix) with ESMTP id C8EF38FC14 for ; Mon, 27 Oct 2008 19:10:32 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from OMTA03.westchester.pa.mail.comcast.net ([76.96.62.27]) by QMTA08.westchester.pa.mail.comcast.net with comcast id Xurb1a0160bG4ec58vABRM; Mon, 27 Oct 2008 19:10:13 +0000 Received: from koitsu.dyndns.org ([69.181.141.110]) by OMTA03.westchester.pa.mail.comcast.net with comcast id XvAU1a00L2P6wsM3PvAVRn; Mon, 27 Oct 2008 19:10:29 +0000 X-Authority-Analysis: v=1.0 c=1 a=KeEtZEhZrkgA:10 a=ieuqav0nqiAA:10 a=QycZ5dHgAAAA:8 a=kcbmCjinaA4WLZLc50YA:9 a=sNbbPtsaESYYmWGSmi_yK2Ce7K8A:4 a=EoioJ0NPDVgA:10 a=LY0hPdMaydYA:10 Received: by icarus.home.lan (Postfix, from userid 1000) id 781BFC9419; Mon, 27 Oct 2008 12:10:28 -0700 (PDT) Date: Mon, 27 Oct 2008 12:10:28 -0700 From: Jeremy Chadwick To: martinko Message-ID: <20081027191028.GA28688@icarus.home.lan> References: <4905951B.2050602@sh.cvut.cz> <20081027160828.GA24496@icarus.home.lan> <4905F8BB.3080302@sh.cvut.cz> <20081027175337.GA27175@icarus.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Cc: freebsd-stable@freebsd.org Subject: Re: Short SMART check causes disk op timeouts X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Oct 2008 19:10:33 -0000 On Mon, Oct 27, 2008 at 07:52:01PM +0100, martinko wrote: > Jeremy Chadwick wrote: >>>>> >>>>> Now, does the timeout cause loss of any data? Is there anything besides >>>>> disabling the testing that I can do about it? >>>> Do you understand what short and long offline tests actually do and what >>>> they're used for? :-) If so, you'd know that running them periodically >>>> is more or less silly (IMHO). >>> I do not, not completely :) I think I have just copied the settings from >>> somewhere and only just tweaked it a bit whenever I have added a disk. >> >> Let me know if you figure out who or what online resource solicited >> adding daily short/long tests, as I'd like to talk to them about their >> decision. I have a feeling whoever thought it up felt that the tests >> were performing entire sector scans of the entire disk, which is simply >> not the case. >> > > Hallo, > > Reading this thread I checked my config to find this: ;-) > > #/dev/ad0 -a -n standby,q -o on -S on -s (S/../.././02|L/../../7/03) -m > root # ++ 2006-11-03 mato > /dev/ad0 -a -o on -S on -s (S/../.././02|L/../../7/03) -m root # ++ > 2006-11-03 mato > > I believe I came up with the settings after reading manual page / > documentation of the tool. Can you explain why you're doing this? So far no one's provided a reason *why* they're doing short and long offline scans on a daily basis. I'm under the impression the conclusion was reached like this: "man smartd.conf ... oh, -s, a neat thing, let's enable it". There are negative repercussions to doing tests of this nature at such regular intervals. Once-a-week is borderline acceptable; once a month would be quite reasonable. I'd love to know what kind of affect daily tests have on MTBF; I can imagine it's reached much sooner with this. The main point of smartd is to monitor SMART attribute changes. If you're concerned about the health of your hard disk, you should be looking at your logs and not relying on things like automatic short/long tests. Most SMART attributes are updated immediately and not during an offline test, and all of those attribute changes will be logged. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |