From owner-freebsd-fs@FreeBSD.ORG Mon Aug 29 20:28:25 2011 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 E8F411065678 for ; Mon, 29 Aug 2011 20:28:25 +0000 (UTC) (envelope-from ee@athyriogames.com) Received: from madonna.sslcatacombnetworking.com (madonna.sslcatacombnetworking.com [174.133.19.130]) by mx1.freebsd.org (Postfix) with ESMTP id BA4318FC18 for ; Mon, 29 Aug 2011 20:28:25 +0000 (UTC) Received: from c-98-206-215-156.hsd1.in.comcast.net ([98.206.215.156] helo=laptopv) by madonna.sslcatacombnetworking.com with esmtpa (Exim 4.69) (envelope-from ) id 1Qy797-0000Yz-A0 for freebsd-fs@freebsd.org; Mon, 29 Aug 2011 14:05:21 -0500 From: "Engineering" To: Date: Mon, 29 Aug 2011 14:15:08 -0500 Message-ID: <01c801cc667f$f99eb7b0$ecdc2710$@com> MIME-Version: 1.0 X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: Acxmf/bkxg/WNgMwTaWJDIhaLpbyEA== Content-Language: en-us X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - madonna.sslcatacombnetworking.com X-AntiAbuse: Original Domain - freebsd.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - athyriogames.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Read-only disk problem 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: Mon, 29 Aug 2011 20:28:26 -0000 Hello all. Please let me know if this is the wrong place to ask. I am working on an embedded system using FreeBSD 7.2, bootinf and running off of flash memory. In order to not burn out the flash, I use the 'diskless' scripts and mount the flash read-only. I have used this configuration successfully in the past. I've recently added a utility to check for disk corruption, basically checksumming the / and /usr partitions. Since they are both read-only, I thought this would work. What I have discovered is that something in the partition is changing between boots. I dd'd the flash over a couple of boots, and compared the binaries to see what was changing. It is a small amount of data, spread across the disk, in an interval that looks very similar to the interval of the 'superblocks' Is there any data that is written to the disk at boot or mount time, and if so, is there a way to prevent it? Thanks Sam