From owner-freebsd-fs@FreeBSD.ORG Wed Nov 3 03:05:18 2010 Return-Path: Delivered-To: fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EBB33106564A for ; Wed, 3 Nov 2010 03:05:17 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta01.emeryville.ca.mail.comcast.net (qmta01.emeryville.ca.mail.comcast.net [76.96.30.16]) by mx1.freebsd.org (Postfix) with ESMTP id CA0E68FC08 for ; Wed, 3 Nov 2010 03:05:17 +0000 (UTC) Received: from omta13.emeryville.ca.mail.comcast.net ([76.96.30.52]) by qmta01.emeryville.ca.mail.comcast.net with comcast id SCV61f00617UAYkA1T5Hf5; Wed, 03 Nov 2010 03:05:17 +0000 Received: from koitsu.dyndns.org ([98.248.41.155]) by omta13.emeryville.ca.mail.comcast.net with comcast id ST5G1f0053LrwQ28ZT5GKV; Wed, 03 Nov 2010 03:05:16 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id F21F29B422; Tue, 2 Nov 2010 20:05:15 -0700 (PDT) Date: Tue, 2 Nov 2010 20:05:15 -0700 From: Jeremy Chadwick To: "Mikhail T." Message-ID: <20101103030515.GA61758@icarus.home.lan> References: <4CD04AEC.8040607@aldan.algebra.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CD04AEC.8040607@aldan.algebra.com> User-Agent: Mutt/1.5.21 (2010-09-15) Cc: fs@freebsd.org Subject: Re: Using an SSD "disk" for / 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: Wed, 03 Nov 2010 03:05:18 -0000 On Tue, Nov 02, 2010 at 01:31:24PM -0400, Mikhail T. wrote: > I'm setting up a new system and would like to use a moderate (64Gb > or 128Gb) SSD-drive to boot from. > > This will house /, /var, /home, and the /usr/local and thus see > plenty of activity, whenever src and ports are updated, or "world" > is remade, or packages are upgraded. I'm hoping, these operations > would be much faster, than with a regular HDD. > > However, people mention, that SSDs develop /severe/ performance > degradation if written to A LOT -- unless some SDD-specific > operation (TRIM) is used, but not all Operating Systems support > that... Does FreeBSD-8? Is that sufficient, or will an SSD degrade > quickly anyway? > > Does anyone use an SSD under FreeBSD? Which brand/model? Are you > happy with it? > > Also, what parameters should I give to newfs? SSDs' characteristics > seem rather different from HDDs', so it is unlikely, that newfs' > defaults will be optimal for an SSD... Would a different filesystem > (ZFS?) be a better choice, than FFS, for these devices? Yes, I use SSDs as the OS disk. Depending on the system's needs, I use one of the following models: - Intel X25-V 40GB - Intel X25-M 80GB The reason I go with Intel disks is because they dominate all other SSD brands when it comes to IOPS. I'm less interested in sequential throughput in this particular case. I also go with Intel because I have a pretty severe dislike for OCZ products (and that's my problem/issue not yours). I use UFS2 + softupdates on all filesystems on the SSDs (except for the root filesystem, which lacks SU). Those filesystems are /, swap, /usr, /tmp, and /var. I do not do any "tuning" of the filesystems either, so I imagine there's room for speed improvements there as well. As for the performance: it's something you'll have to see for yourself. The performance is outright amazing when it comes to administrative tasks (OS installation, newfs, massive copies of data to/from the SSD, updating /usr/src and /usr/ports, etc.). Try a build/install world or kernel sometime on an SSD and watch your terminal. You'll be pretty impressed. Our systems which use SSDs *always* have at least one mechanical HDD included in the system (in fact usually 3, using ZFS raidz1). These are used for things like /var/mail and /home. As for TRIM and the like -- yes, that's a concern of mine as well, but for right now I just monitor the SSDs with smartmontools 5.40 and smartctl -a. If I had to make a recommendation of which drive to get, I would say get a drive that offers at least 80GB. I have to make some sacrifices with the 40GB. Having swap and /var (thus /var/crash) that's big enough to handle a kernel panic is important to me, so effectively the more RAM's in the machine the bigger the SSD needs to be. 80GB seems to be okay for our setups. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |