From owner-freebsd-stable@FreeBSD.ORG Mon Aug 27 20:16:08 2012 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 7E5F9106564A for ; Mon, 27 Aug 2012 20:16:08 +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 199E48FC12 for ; Mon, 27 Aug 2012 20:16:07 +0000 (UTC) Received: from wonkity.com (localhost [127.0.0.1]) by wonkity.com (8.14.5/8.14.5) with ESMTP id q7RKG6qA049540; Mon, 27 Aug 2012 14:16:06 -0600 (MDT) (envelope-from wblock@wonkity.com) Received: from localhost (wblock@localhost) by wonkity.com (8.14.5/8.14.5/Submit) with ESMTP id q7RKG5sj049537; Mon, 27 Aug 2012 14:16:06 -0600 (MDT) (envelope-from wblock@wonkity.com) Date: Mon, 27 Aug 2012 14:16:05 -0600 (MDT) From: Warren Block To: Kevin Oberman In-Reply-To: Message-ID: References: <2d4dfcb2637f4d0e9671899538b603d9@xtaz.co.uk> <67DFAA78-A9A2-49F9-9C29-CA5653ECE3C0@lassitu.de> <20120827172650.7e6a7685@AMD620.ovitrap.com> <78f8335e54e04f158609f0382afb8d4d@xtaz.co.uk> 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]); Mon, 27 Aug 2012 14:16:06 -0600 (MDT) Cc: Erich Dollansky , freebsd-stable@freebsd.org, Stefan Bethke , Matt Smith Subject: Re: 9.1 RELENG_9 Unable to cleanly dismount root partition on shutdown 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: Mon, 27 Aug 2012 20:16:08 -0000 On Mon, 27 Aug 2012, Kevin Oberman wrote: >> No obvious problems jumped out at me. Here are my notes: >> http://www.wonkity.com/~wblock/docs/html/disksetup.html >> >> The gpart version is halfway down. I really need to switch that around. > > Pretty good page, but I would really suggest that you also do either > 4k or 1M alignment on your partitions. If you don't and use a disk > with 4K blocks (internally), you will have terrible performance. You mean add the -a parameter for gpart? All that -a does is round partition starting blocks and sizes to even values. If the numbers given are already even multiples, it does nothing. The reason -a4k is not shown there is because until a few months ago, -a overrode -b. So # gpart add -t freebsd-ufs -l gprootfs -a4k -b 1M -s 2G da0 did not start that partition at 1M, but instead at the next even 4K block after the first 512K partition; block 1064 instead of block 2048, AFAIR. The fix to gpart (thanks to ae@) is in 9-stable and 9.1, but not earlier releases. Mentioned a little farther down in the article is that keeping additional partitions to even multiples of 1M or 1G size will keep them in alignment. > 1M is recommended by Microsoft and used by Windows, but seems a bit > excessive to me. Also by some Sun RAID controllers and other systems. 1M is a nice even multiple of a lot of common block sizes.