From owner-svn-doc-all@FreeBSD.ORG Wed Jan 23 02:48:29 2013 Return-Path: Delivered-To: svn-doc-all@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 4609E757; Wed, 23 Jan 2013 02:48:29 +0000 (UTC) (envelope-from eadler@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) by mx1.freebsd.org (Postfix) with ESMTP id 28EFA2FD; Wed, 23 Jan 2013 02:48:29 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.5/8.14.5) with ESMTP id r0N2mT7k017883; Wed, 23 Jan 2013 02:48:29 GMT (envelope-from eadler@svn.freebsd.org) Received: (from eadler@localhost) by svn.freebsd.org (8.14.5/8.14.5/Submit) id r0N2mTiX017882; Wed, 23 Jan 2013 02:48:29 GMT (envelope-from eadler@svn.freebsd.org) Message-Id: <201301230248.r0N2mTiX017882@svn.freebsd.org> From: Eitan Adler Date: Wed, 23 Jan 2013 02:48:29 +0000 (UTC) To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r40723 - head/en_US.ISO8859-1/books/faq X-SVN-Group: doc-head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-doc-all@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the entire doc trees \(except for " user" , " projects" , and " translations" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Jan 2013 02:48:29 -0000 Author: eadler Date: Wed Jan 23 02:48:28 2013 New Revision: 40723 URL: http://svnweb.freebsd.org/changeset/doc/40723 Log: Wes gesund obsolete section: dangerously-dedicated Noted by: nwhitehorn Aproved by: bcr (mentor, implicit) Modified: head/en_US.ISO8859-1/books/faq/book.xml Modified: head/en_US.ISO8859-1/books/faq/book.xml ============================================================================== --- head/en_US.ISO8859-1/books/faq/book.xml Wed Jan 23 02:42:58 2013 (r40722) +++ head/en_US.ISO8859-1/books/faq/book.xml Wed Jan 23 02:48:28 2013 (r40723) @@ -3550,110 +3550,6 @@ kern.sched.name: ULE - - Will a dangerously dedicated disk - endanger my health? - - - - The installation procedure allows - you to chose two different methods in partitioning your hard - disk(s). The default way makes it compatible with other - operating systems on the same machine, by using - &man.fdisk.8; table entries (called slices in - &os;), with a &os; slice that employs partitions of its own. - Optionally, one can chose to install a boot-selector to - switch between the possible operating systems on the - disk(s). The alternative uses the entire disk for &os;, and - makes no attempt to be compatible with other operating - systems. - - So why it is called dangerous? A disk in - this mode does not contain what normal PC utilities would - consider a valid &man.fdisk.8; table. Depending on how well - they have been designed, they might complain at you once - they are getting in contact with such a disk, or even worse, - they might damage the BSD bootstrap without even asking or - notifying you. In addition, the dangerously - dedicated disk's layout is known to confuse some - BIOSes. - Symptoms of this confusion include the read - error message printed by the &os; bootstrap when - it cannot find itself, as well as system lockups when - booting. - - Why have this mode at all then? It only saves a few - kbytes of disk space, and it can cause real problems for a new - installation. Dangerously dedicated mode's - origins lie in a desire to avoid one of the most common - problems plaguing new &os; installers — matching the - BIOS geometry numbers for a disk to the disk - itself. - - Geometry is an outdated concept, but one - still at the heart of the PC's BIOS and its interaction with - disks. When the &os; installer creates slices, it has to - record the location of these slices on the disk in a fashion - that corresponds with the way the BIOS expects to find them. - If it gets it wrong, you will not be able to boot. - - Dangerously dedicated mode tries to work - around this by making the problem simpler. In some cases, - it gets it right. But it is meant to be used as a - last-ditch alternative — there are better ways to - solve the problem 99 times out of 100. - - So, how do you avoid the need for DD mode - when you are installing? Start by making a note of the - geometry that your BIOS claims to be using for your disks. - You can arrange to have the kernel print this as it boots by - specifying at the - boot: prompt, or using - boot -v in the loader. Just before the - installer starts, the kernel will print a list of BIOS - geometries. Do not panic — wait for the installer to - start and then use scrollback to read the numbers. - Typically the BIOS disk units will be in the same order that - &os; lists your disks, first IDE, then SCSI. - - When you are slicing up your disk, check that the disk - geometry displayed in the FDISK screen is correct (i.e., it - matches the BIOS numbers); if it is wrong, use - G to fix it. You may have to do this - if there is absolutely nothing on the disk, or if the disk - has been moved from another system. Note that this is only - an issue with the disk that you are going to boot from; &os; - will sort itself out just fine with any other disks you may - have. - - Once you have got the BIOS and &os; agreeing about the - geometry of the disk, your problems are almost guaranteed to - be over, and with no need for DD mode at all. - If, however, you are still greeted with the dreaded - read error message when you try to - boot, it is time to cross your fingers and go for it — there - is nothing left to lose. - - To return a dangerously dedicated disk - for normal PC use, there are basically two options. The - first is, you write enough NULL bytes over the MBR to make - any subsequent installation believe this to be a blank disk. - You can do this for example with the following - command: - - &prompt.root; dd if=/dev/zero of=/dev/rda0 count=15 - - Alternatively, the undocumented DOS - feature - - C:\> fdisk /mbr - - will to install a new master boot record as well, thus - clobbering the BSD bootstrap. - - - - Which partitions can safely use Soft Updates? I have heard that Soft Updates on / can cause