From owner-freebsd-performance@FreeBSD.ORG Mon Feb 25 01:32:32 2008 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9B2C316A400 for ; Mon, 25 Feb 2008 01:32:32 +0000 (UTC) (envelope-from chrcoluk@gmail.com) Received: from ug-out-1314.google.com (ug-out-1314.google.com [66.249.92.175]) by mx1.freebsd.org (Postfix) with ESMTP id 4092913C469 for ; Mon, 25 Feb 2008 01:32:32 +0000 (UTC) (envelope-from chrcoluk@gmail.com) Received: by ug-out-1314.google.com with SMTP id y2so691371uge.37 for ; Sun, 24 Feb 2008 17:32:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; bh=r8PCbcPmO3L27wZMF5i9jRZVp1lNyJDVOgU+9sHvEiw=; b=cmwu3EW7UQ9/NZBlNWN4szFv6jXcpWolZwBXy23H3sUKaV5Gq+OOp5cIWkE4/s9/a374c+4qeM8mLmehz5PW4UsTiiuEkmCOPjzaAkvY7+0UiWjhOEA/ySoViuoATJS8qO4tMqgKH9HG0hO6LurBrLg8ZF2+6b87MolpLt7ky0w= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=ZZSFAq+SjuNfRV9KEnRFg6cVqT2Se8vyXHtIOFOXFwea6pb6TXlbSfART0IS7Gq1NLRN1ZxgaQqONBVsPr3L/us6JnmYtdah0OGVI/+lDoK0NnhPvAcL7qXmyZVNxZRVKNUnCYdpmv3dtGNrV9Ky/RLed8J3dJWLdJsXOaxgY8c= Received: by 10.66.237.14 with SMTP id k14mr2426684ugh.72.1203901525390; Sun, 24 Feb 2008 17:05:25 -0800 (PST) Received: by 10.66.219.18 with HTTP; Sun, 24 Feb 2008 17:05:25 -0800 (PST) Message-ID: <3aaaa3a0802241705k749cc4a2n9b668c6b22339824@mail.gmail.com> Date: Mon, 25 Feb 2008 01:05:25 +0000 From: Chris To: freebsd-performance@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Subject: maxphys and block sizes on slices X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Feb 2008 01:32:32 -0000 Hi. I got a server that is primarily handling large files not massive files but files that are 15meg+ in size and very few smaller files. So I decided to use the following options in newfs. -f 4096 -b 32768 Eventually I realised this was a bad decision especially when I noticed vfs.bufdefragcnt growing. In addition I have noticed all servers that are using the default settings have 128kbytes per transfer and appear to use what maxphys is set to whilst the ones with the custom newfs options are locked to 64kb/transfer even if dfltphys and maxphys are increased. I did increase BKVASIZE to 32768 to stop the bufdefragcnt tho. My lesson is learned tho new servers I setup I will keep the default block sizes unless someone has experience of better settings. For now I want to make the best of the settings I got in place. 1 - is the 64kB per transfer not adjustable and is a penalty for choosing the large block size? It is nearly always penned at 64kB with 100s transfers per second. 2 - is there a way to adjust the block sizes without wiping the data? 3 - How big an impact does a growing vfs.bufdefragcnt make on performance? after I fixed it I have noticed no difference. 4 - Is there anything in general reccomended to set for a server that handles large files but not many of them. 5 - What are the reccomended values on newfs for large files, the defaults? and does the 1/8th rule have to apply for frag size vs block size? 6 - finally I have read vfs.hirunningspace boosts write speeds by buffering more but it can be detrimental to read speeds is this true? Thanks