svn commit: r40723 - head/en_US.ISO8859-1/books/faq

Eitan Adler eadler at
Wed Jan 23 02:48:29 UTC 2013

Author: eadler
Date: Wed Jan 23 02:48:28 2013
New Revision: 40723

  Wes gesund obsolete section: dangerously-dedicated
  Noted by:	nwhitehorn
  Aproved by:	bcr (mentor, implicit)


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 @@ ULE</screen>
-	<question id="dangerously-dedicated">
-	  <para>Will a <quote>dangerously dedicated</quote> disk
-	    endanger my health?</para>
-	</question>
-	<answer>
-	  <para><anchor id="dedicate"/>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 <quote>slices</quote> 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.</para>
-	  <para>So why it is called <quote>dangerous</quote>?  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 <quote>dangerously
-	    dedicated</quote> disk's layout is known to confuse some
-	    BIOSes.
-	    Symptoms of this confusion include the <errorname>read
-	    error</errorname> message printed by the &os; bootstrap when
-	    it cannot find itself, as well as system lockups when
-	    booting.</para>
-	  <para>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.  <quote>Dangerously dedicated</quote> mode's
-	    origins lie in a desire to avoid one of the most common
-	    problems plaguing new &os; installers — matching the
-	    BIOS <quote>geometry</quote> numbers for a disk to the disk
-	    itself.</para>
-	  <para><quote>Geometry</quote> 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.</para>
-	  <para><quote>Dangerously dedicated</quote> 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.</para>
-	  <para>So, how do you avoid the need for <quote>DD</quote> 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 <option>-v</option> at the
-	    <literal>boot:</literal> prompt, or using
-	    <command>boot -v</command> 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.</para>
-	  <para>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
-	    <keycap>G</keycap> 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.</para>
-	  <para>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 <quote>DD</quote> mode at all.
-	    If, however, you are still greeted with the dreaded
-	    <errorname>read error</errorname> message when you try to
-	    boot, it is time to cross your fingers and go for it — there
-	    is nothing left to lose.</para>
-	  <para>To return a <quote>dangerously dedicated</quote> 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:</para>
-	  <screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/<replaceable>rda0</replaceable> count=15</userinput></screen>
-	  <para>Alternatively, the undocumented DOS
-	    <quote>feature</quote></para>
-	  <screen><prompt>C:\></prompt> <userinput>fdisk /mbr</userinput></screen>
-	  <para>will to install a new master boot record as well, thus
-	    clobbering the BSD bootstrap.</para>
-	</answer>
-      </qandaentry>
-      <qandaentry>
 	<question id="safe-softupdates">
 	  <para>Which partitions can safely use Soft Updates?  I have
 	    heard that Soft Updates on <filename class="directory">/</filename> can cause

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