From owner-freebsd-questions@FreeBSD.ORG Fri Nov 23 05:56:58 2012 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 15D4FC19 for ; Fri, 23 Nov 2012 05:56:58 +0000 (UTC) (envelope-from wblock@wonkity.com) Received: from wonkity.com (wonkity.com [67.158.26.137]) by mx1.freebsd.org (Postfix) with ESMTP id 9DB988FC12 for ; Fri, 23 Nov 2012 05:56:57 +0000 (UTC) Received: from wonkity.com (localhost [127.0.0.1]) by wonkity.com (8.14.5/8.14.5) with ESMTP id qAN5upgH017449; Thu, 22 Nov 2012 22:56:51 -0700 (MST) (envelope-from wblock@wonkity.com) Received: from localhost (wblock@localhost) by wonkity.com (8.14.5/8.14.5/Submit) with ESMTP id qAN5uoE1017361; Thu, 22 Nov 2012 22:56:51 -0700 (MST) (envelope-from wblock@wonkity.com) Date: Thu, 22 Nov 2012 22:56:50 -0700 (MST) From: Warren Block To: Shane Ambler Subject: Re: FreeBSD on SSD on ASUS P5KPL-C In-Reply-To: <50AEDD3E.8030007@ShaneWare.Biz> Message-ID: References: <50A83993.50401@ShaneWare.Biz> <50AEDD3E.8030007@ShaneWare.Biz> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (wonkity.com [127.0.0.1]); Thu, 22 Nov 2012 22:56:51 -0700 (MST) Cc: freebsd questions list X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Nov 2012 05:56:58 -0000 On Fri, 23 Nov 2012, Shane Ambler wrote: > On 22/11/2012 14:49, Warren Block wrote: >> On Wed, 21 Nov 2012, Warren Block wrote: >> >>> Got a chance to set up a scratch drive and check this. Turns out >>> I left out the step of creating a "slice" (MBR partition) to hold >>> the FreeBSD partitions. Also, GPT labels cannot be used in an >>> MBR. Fixed below. I will probably add this to my disk setup >>> article because it has come up more than once. >> >> The fdisk/bsdlabel section of my disk setup article has been >> rewritten to use gpart. Feedback welcome. >> >> http://www.wonkity.com/~wblock/docs/html/disksetup.html > > Something I meant to ask before - is there any benefit to following the > steps described in > http://www.aisecure.net/2012/01/16/rootzfs/ My guide is based on using UFS. ZFS or other filesystems will also benefit from block alignment, but the methods to get there can be different. > The step of using gnop is meant to trick zfs into believing the disk has > 4K sector size to improve performance, which I would think zfs would be > able to figure out by talking to the disk. Unless ZFS is put on a bare, unpartitioned disk, configuration for performance is better left to the user. It's a pain to correct automatic configs when they guess wrong. > Does partitioning hide the sector size or would the step of aligning > the partition start to a 4k sector unhide the 4k size? > Or are these steps just a waste of time? It's not about hiding the device's native block size, it's about getting the filesystem to do aligned I/O so the device can just read or write a single 4K block instead of part of one and part of another.