From owner-freebsd-current@FreeBSD.ORG Wed Mar 25 12:55:41 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5034B1065689 for ; Wed, 25 Mar 2009 12:55:41 +0000 (UTC) (envelope-from alexander@leidinger.net) Received: from redbull.bpaserver.net (redbullneu.bpaserver.net [213.198.78.217]) by mx1.freebsd.org (Postfix) with ESMTP id A9E1E8FC16 for ; Wed, 25 Mar 2009 12:55:40 +0000 (UTC) (envelope-from alexander@leidinger.net) Received: from outgoing.leidinger.net (pD9E2D310.dip.t-dialin.net [217.226.211.16]) by redbull.bpaserver.net (Postfix) with ESMTP id CEEBD2E0A5; Wed, 25 Mar 2009 13:55:33 +0100 (CET) Received: from webmail.leidinger.net (webmail.leidinger.net [192.168.1.102]) by outgoing.leidinger.net (Postfix) with ESMTP id 743692042E4; Wed, 25 Mar 2009 13:55:30 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=Leidinger.net; s=outgoing-alex; t=1237985730; bh=Iy8p41orq8CiFH4VNqNNv1m0MrvWmRXHI iOa74pMUV8=; h=Message-ID:Date:From:To:Cc:Subject:References: In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=UkBpZOrFL51QyGwKHJ4rQZVCQ07waXBRTKDGwOPg94X2zbPoEQoF8GoSchqRiHjzf oTPAaXs0yPgmJtRxN13YrpZKddwkYxhc26exBq7PqdQfV/Iur6luESA8GeeBMvwxTBv vEm6yokX0prwZWTChfaS/j1Q1tKhzP7GAJBQio5qQ4pkZVxByNqUnDv5wRoVTeEdhMg EDK26C3wHyA3vEljM+bSc91Qf0W6lgnc65do8VE09+zdILY3mHmmMMr3XtBMb4b22Xw qpv77+4cfKzvLkeXLRuSjZHle/dMdDLNRmWyCTksMDdYhalsF1pnzxaKlcrJllspnYH ZibQkS2Yw== Received: (from www@localhost) by webmail.leidinger.net (8.14.3/8.13.8/Submit) id n2PCtTaR050983; Wed, 25 Mar 2009 13:55:29 +0100 (CET) (envelope-from Alexander@Leidinger.net) Received: from pslux.cec.eu.int (pslux.cec.eu.int [158.169.9.14]) by webmail.leidinger.net (Horde Framework) with HTTP; Wed, 25 Mar 2009 13:55:28 +0100 Message-ID: <20090325135528.21416hzpozpjst8g@webmail.leidinger.net> X-Priority: 3 (Normal) Date: Wed, 25 Mar 2009 13:55:28 +0100 From: Alexander Leidinger To: Mark Powell References: <49BD117B.2080706@163.com> <4F9C9299A10AE74E89EA580D14AA10A635E68A@royal64.emp.zapto.org> <49BE4EC1.90207@163.com> <20090320102824.W75873@rust.salford.ac.uk> <20090320152737.D641@rust.salford.ac.uk> <20090325105613.55624rkkgf2xkr6s@webmail.leidinger.net> <20090325103721.G67233@rust.salford.ac.uk> In-Reply-To: <20090325103721.G67233@rust.salford.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; DelSp="Yes"; format="flowed" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable User-Agent: Internet Messaging Program (IMP) H3 (4.3) / FreeBSD-8.0 X-BPAnet-MailScanner-Information: Please contact the ISP for more information X-MailScanner-ID: CEEBD2E0A5.B8BA6 X-BPAnet-MailScanner: Found to be clean X-BPAnet-MailScanner-SpamCheck: not spam, ORDB-RBL, SpamAssassin (not cached, score=-12.827, required 6, BAYES_00 -15.00, DKIM_SIGNED 0.00, DKIM_VERIFIED -0.00, J_CHICKENPOX_37 0.60, MIME_QP_LONG_LINE 1.40, RDNS_DYNAMIC 0.10, TW_ZF 0.08) X-BPAnet-MailScanner-From: alexander@leidinger.net X-Spam-Status: No Cc: kevin , FreeBSD Current , Daniel Eriksson Subject: Re: Apparently spurious ZFS CRC errors (was Re: ZFS data error without reasons) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Mar 2009 12:55:42 -0000 Quoting Mark Powell (from Wed, 25 Mar 2009 =20 10:45:43 +0000 (GMT)): > On Wed, 25 Mar 2009, Alexander Leidinger wrote: > >> Quoting Mark Powell (from Fri, 20 Mar =20 >> 2009 15:30:11 +0000 (GMT)): >>> Hmmm. Perhaps I'm not being fair on 8. Just had a look at my =20 >>> loader.conf for 7 and I can see that I used to run with every =20 >>> zfs*disable on. I've just rebooted 8 with: >>> >>> vfs.zfs.cache_flush_disable: 1 >>> vfs.zfs.mdcomp_disable: 1 >>> vfs.zfs.prefetch_disable: 1 >>> vfs.zfs.zil_disable: 1 >>> hw.ata.wc: 1 >>> >>> The current fs which produced errors on every scrub now reports no error= s. >>> I now need to find which option fixed it. >>> I suspect hw.ata.wc. Is this still a known issue? > > Alex, > Thanks for the input, > >> I would expect that it is the combination of cache_flush_disable =20 >> and zil_disable with the wc enable. If you reenable the zil and the =20 >> cache flush, the wc should not cause the problems you see. You may =20 >> want to have a look at =20 >> http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide for = a =20 >> more detailed description of what those options are doing (and why =20 >> you should not disable those features on normal disks). I also =20 >> suggest to not disable the meta-data compression, as it seems it =20 >> only affects a small amount of meta-data instead of all meta-data. > > I initially ran 8 with default options i.e. write caching on, all =20 > zfs options left enabled. I got the errors. Only then did I try =20 > changing options, by turning off wc and disabling zfs options. > It's a little curious that I should reenable the wc, and all zfs =20 > options except prefetch_disable. That takes me back to how I =20 > originally started, but with the solution to the problem therefore =20 > being disabling the prefetch. > Can prefetch really cause these problems? And if so why? I don't think so. I missed the part where you explained this before. =20 In this case it's really the write cache. The interesting questions is =20 if this is because of the harddisks you use, or because of a bug in =20 the software. You run a very recent current? 1-2 weeks before there was a bug (not =20 in ZFS) which caused CRC errors, but it was fixed shortly after it was =20 noticed. If you haven't updated your system, it may be best to update =20 it and try again. Please report back. >> If you want to get more out of zfs, maybe vfs.zfs.vdev.max_pending =20 >> could help if you are using SATA (as I read the zfs tuning guide, =20 >> it makes sense to have a high value when you have command queueing, =20 >> which we have with SCSI drives, but not yet with SATA drives and =20 >> probably not at all with PATA drives). > > I'm running completely SATA with NCQ supporting drives. However, and =20 > possibly as you say, NCQ is not really/properly supported in FBSD? NCQ is not supported yet in FreeBSD. Alexander Motin said he is =20 interested in implementing it, but I don't know about the status of =20 this. Bye, Alexander. --=20 Your business will assume vast proportions. http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID =3D B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID =3D 72077137