From owner-freebsd-fs@FreeBSD.ORG Sun Jun 21 22:57:21 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 97689106564A for ; Sun, 21 Jun 2009 22:57:21 +0000 (UTC) (envelope-from dan.naumov@gmail.com) Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.30]) by mx1.freebsd.org (Postfix) with ESMTP id 4BDB68FC24 for ; Sun, 21 Jun 2009 22:57:21 +0000 (UTC) (envelope-from dan.naumov@gmail.com) Received: by yw-out-2324.google.com with SMTP id 9so1274236ywe.13 for ; Sun, 21 Jun 2009 15:57:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=o4hQJlA1mBE06J8PuDaiAH/MRe7g8NWWX9DPUjjRW8A=; b=I5v/5wP1aAbCRFnaMC0ZxO73+XVdEa/J0661L5+/s4INPPBmDKafKPlp8fkicjwXyg fqskBHiFZMAvyeOw7xSQ/pTPwNvOfldT3adzRAfahcPYoPodEWG/o0XSOxOdZFdOYFKZ IGLmn8Xo7tpmWKY8HwQ6eNcA19aPMIKlGSwvI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=N5ANwGKFtQH9wFqAQIMeTnyKk28iQw9xz1C2uRedvpL93V2WzHmoYqm9qVUEVj7spE E8zTUjx/dGM65i+JVI/lKZ/pwOG4acYmRsFxd5w6zznoe/3fWCvxzpeYgbXqRZaSd/gS cp6UHMpalU6F2hwL8nAFFV4JLVpRoXSlNC2/8= MIME-Version: 1.0 Received: by 10.100.251.6 with SMTP id y6mr7192796anh.44.1245625040447; Sun, 21 Jun 2009 15:57:20 -0700 (PDT) In-Reply-To: <570433.20373.qm@web37308.mail.mud.yahoo.com> References: <570433.20373.qm@web37308.mail.mud.yahoo.com> Date: Mon, 22 Jun 2009 01:57:20 +0300 Message-ID: From: Dan Naumov To: =?windows-1252?Q?=8Aimun_Mikecin?= Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 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: Sun, 21 Jun 2009 22:57:22 -0000 2009/6/21 =8Aimun Mikecin > > 21. lip. 2009., u 13:41, Andrew Snow napisao: > > Folks who need to maximize safety and can't afford the performance > > hit of no write cache need to do what they always have had to do in > > the past - buy a controller card with battery-backed cached. > > Or: > B) use SCSI instead of ATA disks > C) use UFS+gjournal instead of UFS+SU > D) use ZFS instead of UFS+SU Actually I think a need a few clarifications regarding ZFS: 1) Does FreeBSD honor the "flush the cache to disk now" commands issued by ZFS to the harrdive only when ZFS is used directly on top of a disk device directly or does this also work when ZFS is used on top of a slice/partition? 2) If we compare ZFS vs UFS+SU while using a regular "lying" SATA disk (wit= h write cache enabled) under heavy IO followed by a power loss. Which one is going to recover better and why? Sincerely, - Dan Naumov