svn commit: r40723 - head/en_US.ISO8859-1/books/faq
Eitan Adler
eadler at FreeBSD.org
Wed Jan 23 02:48:29 UTC 2013
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</screen>
</qandaentry>
<qandaentry>
- <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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