From owner-freebsd-stable@FreeBSD.ORG Sun Apr 3 10:53:01 2011 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 7790A106564A for ; Sun, 3 Apr 2011 10:53:01 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.cran.org.uk (muon.cran.org.uk [IPv6:2a01:348:0:15:5d59:5c40:0:1]) by mx1.freebsd.org (Postfix) with ESMTP id DA6088FC0C for ; Sun, 3 Apr 2011 10:53:00 +0000 (UTC) Received: from muon.cran.org.uk (localhost [127.0.0.1]) by muon.cran.org.uk (Postfix) with ESMTP id E6313E8136; Sun, 3 Apr 2011 11:52:59 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=cran.org.uk; h=message-id :date:from:mime-version:to:cc:subject:references:in-reply-to :content-type; s=mail; bh=tHWhPV19mf4aKYK7di6ZviUV7sE=; b=IrQZqR wWxLUL8Sl97tY1ESGYQmkZ+2P3Wf+S+XuC8mfx2ATngLs/VUN2kdDwDVWvH75/qp S7qzzm2YVAxRpN2v/C5MJVm/fQQAbPPLO9lbryl0AfTbMX40i+VNKGaiiRrAqfVP P1zG5V+2MKCFuM9IiXG5TdT2iusZ5N1eCPk5k= DomainKey-Signature: a=rsa-sha1; c=nofws; d=cran.org.uk; h=message-id :date:from:mime-version:to:cc:subject:references:in-reply-to :content-type; q=dns; s=mail; b=Cs29Bb9JGxji7sOYI87Ak8ExPQDwOzOu nKwZxzh30paShRW60U8uRPyoRfoMF9t0F4iiu8beyLpIdXraNvef+qARe4BoaG41 3XWCbc37EgaJmGjK9fB2TRXQPJeAVXLYjQD6P+DRGyKWffj88lFrN8npF8g8FeYb Ne97ADIqSos= Received: from [192.168.1.69] (188-222-18-231.zone13.bethere.co.uk [188.222.18.231]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by muon.cran.org.uk (Postfix) with ESMTPSA id A8A10E7B60; Sun, 3 Apr 2011 11:52:59 +0100 (BST) Message-ID: <4D985184.5050409@cran.org.uk> Date: Sun, 03 Apr 2011 11:52:52 +0100 From: Bruce Cran User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 To: "Marat N.Afanasyev" References: <87d3l6p5xv.fsf@cosmos.claresco.hr> <874o6ip0ak.fsf@cosmos.claresco.hr> <4D95F143.8080001@ksu.ru> In-Reply-To: <4D95F143.8080001@ksu.ru> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms070907080703040202040804" X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Marko Lerota , freebsd-stable@freebsd.org Subject: Re: Constant rebooting after power loss 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: Sun, 03 Apr 2011 10:53:01 -0000 This is a cryptographically signed message in MIME format. --------------ms070907080703040202040804 Content-Type: text/plain; charset=KOI8-R; format=flowed Content-Transfer-Encoding: quoted-printable On 01/04/2011 16:37, Marat N.Afanasyev wrote: > to ensure consistency you should turn off physical drive caches, and > degrade performance significantly, sometimes up to 1000x. if this is > what you want, you may use either zfs or sync ufs. in such case you may= > be almost sure that your filesystems are consistent. but if you use > drive's cache, then without UPS you will face data loss and vanished > filesystem earlier or later I'm not sure the performance loss is so severe with modern drives=20 (attached to a decent controller). If they do tagged queuing (NCQ/TCQ) I = think a lot of the performance lost through disabling the write cache=20 can be regained through the queueing system. --=20 Bruce Cran --------------ms070907080703040202040804--