From owner-freebsd-fs@FreeBSD.ORG Fri Jan 15 16:57:15 2010 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 AC5FA106566C; Fri, 15 Jan 2010 16:57:15 +0000 (UTC) (envelope-from dan.naumov@gmail.com) Received: from mail-gx0-f218.google.com (mail-gx0-f218.google.com [209.85.217.218]) by mx1.freebsd.org (Postfix) with ESMTP id 575978FC12; Fri, 15 Jan 2010 16:57:15 +0000 (UTC) Received: by gxk10 with SMTP id 10so607295gxk.3 for ; Fri, 15 Jan 2010 08:57:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:date:message-id:subject :from:to:content-type; bh=006Hy+SzcLW5RyLs66GlTLo0Ty7S4T3T3FNQ3kWQARs=; b=KMhZ2H02rMjQ6mq4nSwiwkfA1VIyRW7VNAuD3puPYyORayUWBZD4/1e5sgjrvbtaCG qv+YFvzsqFxyj5LwfD8qWf9MJt+2U7zlejEQ+NclZoajKS3LXfan+3402/NwUuYnnw69 ombxBBjQP0WHBWRZy1WCAJT0urN+1ZDlx9Kgw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; b=pv6gkrGn3LavsPCWB83E/Fy/cc/Z298CEFzwYJO1vhyBwY3ilLHcPbQWxs2TQAESfa oKOF94ZICFUS7NnonEJSJ7+eYJHVFgSPAPVc1BHz2/ANInKW1VMMvxUO7jhxJtUN2kV+ R+DrAi2vcZzC4R/V9bsGz3EsBc54+MXvukadc= MIME-Version: 1.0 Received: by 10.101.214.5 with SMTP id r5mr5024557anq.3.1263574623123; Fri, 15 Jan 2010 08:57:03 -0800 (PST) Date: Fri, 15 Jan 2010 18:57:03 +0200 Message-ID: From: Dan Naumov To: Rick Macklem , freebsd-questions@freebsd.org, freebsd-fs@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 Cc: Subject: (SOLVED) Re: installing FreeBSD 8 on SSDs and UFS2 - partition alignment, block sizes, what does one need to know? 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: Fri, 15 Jan 2010 16:57:15 -0000 On Fri, Jan 15, 2010 at 6:38 PM, Rick Macklem wrote: > > > On Tue, 12 Jan 2010, Dan Naumov wrote: > >> For my upcoming storage system, the OS install is going to be on a >> 80gb Intel SSD disk and for various reasons, I am now pretty convinced >> to stick with UFS2 for the root partition (the actual data pool will >> be ZFS using traditional SATA disks). I am probably going to use GPT >> partitioning and have the SSD host the swap, boot, root and a few >> other partitions. What do I need to know in regards to partition >> alignment and filesystem block sizes to get the best performance out >> of the Intel SSDs? >> > I can't help with your question, but I thought I'd mention that there > was a recent post (on freebsd-current, I think?) w.r.t. using an SSD > for the ZFS log file. It suggested that that helped with ZFS perf., so > you might want to look for the message. > > rick I have managed to figure out the essential things to know by know, I just wish there was a single, easy to grasp webpage or HOWTO describing and whys and hows so I wouldn't have had had to spend the entire day googling things to get a proper grasp on the issue :) To (perhaps a bit too much) simplify things, if you are using an SSD with FreeeBSD, you: 1) Should use GPT 2) Should create the freebsd-boot partition as normal (to ensure compatibility with some funky BIOSes) 3) All additional partitions should be aligned, meaning that their boundaries should be dividable by 1024kb (that's 2048 "logical blocks" in gpart). Ie, having created your freeebsd-boot, your next partition should start at block 2048 and the partition size should be dividable by 2048 blocks. This applies to ALL further partitions added to the disk, so you WILL end up having some empty space between them, but a few MBs worth of space will be lost at most. P.S: My oversimplification was in that MOST SSDs will be just fine with a 512 kb / 1024 block alignment. However, _ALL_ SSDs will be fine with 1024 kb / 2048 block alignment. - Sincerely, Dan Naumov