From owner-freebsd-fs@FreeBSD.ORG Mon Jun 22 13:06:44 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 28B92106566C for ; Mon, 22 Jun 2009 13:06:44 +0000 (UTC) (envelope-from numisemis@yahoo.com) Received: from web37304.mail.mud.yahoo.com (web37304.mail.mud.yahoo.com [209.191.90.247]) by mx1.freebsd.org (Postfix) with SMTP id D8F288FC17 for ; Mon, 22 Jun 2009 13:06:43 +0000 (UTC) (envelope-from numisemis@yahoo.com) Received: (qmail 94515 invoked by uid 60001); 22 Jun 2009 13:06:43 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1245676003; bh=m1zyiDrryplvFU3JyreKyk15iAU8vqtkTriJ7odmdtQ=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type; b=JHHMDhqDevvylWHvY0vPhEdr33BEw0T6G2FKPr3TXd+kzpOSJU+96AxDsc8Vc43GvqLQ9YlMnLcrP4tfKx/GVzw3qPgaXIptpHRjRcDZ/VYW1TaKWwSAlgkc3vS5YafINpzbPR9oSSwCCkvDbCyTkuSDLPkytwrhSyiKqZ+x7x4= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type; b=cNyPgAgxpfrQBGca9eFLuQp7OiRA1ZIxcIcKikCWhLGtsP6STRHjiX7ndOBpjdiqeyHPxMCd+gPLPyNp5LE2vbVkuMKqzeT+8m7GFHc7p+PC7MmxKDFP5+qW7QykZFJ2Pp4l/IICSEXE9XAV3HH5swvRfj1YOXuusrutZxR8IFw=; Message-ID: <303630.93763.qm@web37304.mail.mud.yahoo.com> X-YMail-OSG: 3AyDROYVM1msTupjQ6DPblfE3I2bJTuGhXYzwDeYlDi2m3W0iGuYKTXR_cd7fqhpH4__ppvfLwWssP15mTMv4iqNPPWXBJz3kDD6t0xcN3jpLbDnANPH4IQRIN1sIxbpBGSmhfoQhCY.Za7ymahN91TEVu.u2fkNRjeYyctOM24mjHTibBL9HdrJr48nf6osj7s_nD59s.8U0RWP0ZobFo7uiDN8pAluFSt.duHqNd1cn5ta8B9lxF_6RdzKt2KXD925TcwWnjThrk3nrAhfcjuAlZZfRHQZpZ0_lgnRUPaDKvF7pQvfDZhiyRQLEwKD3ccmjg-- Received: from [87.252.131.19] by web37304.mail.mud.yahoo.com via HTTP; Mon, 22 Jun 2009 06:06:43 PDT X-Mailer: YahooMailRC/1277.43 YahooMailWebService/0.7.289.15 References: <570433.20373.qm@web37308.mail.mud.yahoo.com> <4A3E9D81.1060406@modulus.org> <4A3EB902.8080503@modulus.org> Date: Mon, 22 Jun 2009 06:06:43 -0700 (PDT) From: Simun Mikecin To: Andrew Snow In-Reply-To: <4A3EB902.8080503@modulus.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: freebsd-fs@freebsd.org Subject: Re: ufs2 / softupdates / ZFS / disk write cache X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jun 2009 13:06:44 -0000 Andrew Snow wrote: > All of these solutions still involve disabling of write cache, with a performance hit of varying degrees. (I have tried all of those except gjournal!) Can you please elaborate this statement? AFAIK all of these solutions are absolutelly safe to use with write cache enabled: - SCSI disks are safe with TCQ enabled (not sure when TCQ is disabled) - UFS+gjournal is safe because of regular disk cache flushing - ZFS is safe by design