doc/handbook/disks.sgml

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     Disks and FreeBSD.  By David O'Brien, 1998.

     $Id: disks.sgml,v 1.3 1998-05-15 09:36:42 obrien Exp $

     The FreeBSD Documentation Project

<!DOCTYPE linuxdoc PUBLIC "-//FreeBSD//DTD linuxdoc//EN">

  <article>
      <title> Disks and FreeBSD
      <author> David O'Brien <tt/obrien@cs.ucdavis.edu/
      <date> 26 April 1998, (c) 1998

      <abstract> This document describes disk administration task under
	FreeBSD.  It tells how to set up disks and bring them online.
	</abstract>

    <toc>
-->

  <chapt><heading>Disks<label id="disks"></heading>

    <p><em>Contributed by &a.obrien;<newline>26 April 1998</em>

	<p>Lets say we want to add a new SCSI disk to a machine that currently
	only has a single drive.  First turn off the computer and install the
	drive in the computer following the instructions of the computer,
	controller, and drive manufacturer.  Due the wide variations of procedures
	to do this, the details are beyond the scope of this document.

	<p>Login as user <it>root</it>.  After you've installed the drive,
	inspect <tt>/var/run/dmesg.boot</tt> to ensure the new disk was found.
	Continuing with our example, the newly added drive will be <tt>sd1</tt>
	and we want to mount it on <tt>/1</tt>.
	(if you are adding an IDE drive substitute <tt>wd</tt> for <tt>sd</tt>)

	<p>Because FreeBSD runs on IBM-PC compatible computers, it must take into
	account the PC BIOS partitions.  These are different from the traditional
	BSD partitions.  A PC disk has up to four BIOS partition entries.  If the
	disk is going to be truly dedicated to FreeBSD, you can use the
	<it>dedicated</it> mode.  Otherwise, FreeBSD will have to live with in
	one of the PC BIOS partitions.  FreeBSD calls the PC BIOS partitions,
	<it>slices</it> so as not to confuse them with traditional BSD
	partitions.  You may also use slices on a disk that is dedicated to
	FreeBSD, but used in a computer that also has another operating system
	installed.  This is to not confuse the <tt>fdisk</tt> utility of the other
	operating system.

	<p>In the slice case the drive will be added as <tt>/dev/sd1s1e</tt>.
	This is read as:  SCSI disk, unit number 1 (second SCSI disk), slice 1
	(PC BIOS partition 1), and <tt>e</tt> BSD partition.
	In the dedicated case, the drive will be added simply as <tt>/dev/sd1e</tt>.

    <sect><heading> Using sysinstall</heading>
	<p> You may use <tt>/stand/sysinstall</tt> to partition and label a new
	disk using its easy to use menus.  Either login as user <it>root</it>
	or use the <tt>su</tt> command.  Run <tt>/stand/sysinstall</tt> and enter
	the <it>Configure</it> menu.  With in the <tt>FreeBSD Configuration
	Menu</tt>, scroll down and select the <it>Partition</it> item.  Next you
	should be presented with a list of hard drives installed in your system.
	If you do not see <tt>sd1</tt> listed, you need to recheck your physical
	installation and <tt>dmesg</tt> output in the file
	<tt>/var/run/dmesg.boot</tt>.

	<p>Select <tt>sd1</tt> to enter the <tt>FDISK Partition Editor</tt>.
	Choose <tt>A</tt> to use the entire disk for FreeBSD.  When asked if you
	want to ``remain cooperative with any future possible operating systems'',
	answer <it>YES</it>.  Write the changes to the disk using <it>W</it>.
	Now exit the FDISK editor using <it>q</it>.
	Next you will be asked about the Master Boot Record.  Since you are
	adding a disk to an already running system, choose <it>None</it>.

	<p>Next enter the <it>Disk Label Editor</it>.  This is where you will
	create the traditional BSD partitions.  A disk can have up to eight
	partitions, labeled a-h.  A few of the partition labels have special
	uses.  The <it>a</it> partition is used for the root partition (/).
	Thus only your system disk (e.g, the disk you boot from) should have
	an <it>a</it> partition.
	The <it>b</it> partition is used for swap partitions, and you may
	have many disks with swap partitions.  The <it>c</it> partition
	addresses the entire disk in dedicated mode, or the entire FreeBSD
	slice in slice mode.  The other partitions are for general use.

	<p>Sysinstall's Label editor favors the <it>e</it> partition for non-root,
	non-swap partitions.  With in the Label editor, create a single file
	system using <it>C</it>.  When prompted if this will be a FS (file 
	system) or swap, choose ``FS'' and give a mount point (e.g, 
	<tt>/mnt</tt>).  When adding a disk in post-install mode, Sysinstall
	will not create entries in <tt>/etc/fstab</tt> for you, so the
	mount point you specify isn't important.

	<p>You are now ready to write the new label to the disk and create a
	file system on it.  Do this by hitting <it>W</it>.  Ignore any errors
	from Sysinstall that it could not mount the new partition.  Exit
	the Label Editor and Sysinstall completely.

	<p>The last step is to edit <tt>/etc/fstab</tt> to add an entry for your
	new disk.

    <sect><heading> Using command line utilities</heading>

    <sect1><heading> * Using Slices</heading>

    <sect1><heading> Dedicated</heading>
	<p>If you will not be sharing the new drive with another operating system,
	you may use the <it>dedicated</it> mode.  Remember this mode can confuse
	Microsoft operating systems; however, no damage will be done by them.
	IBM's OS/2 however, will "appropriate" any partition it finds which
	it doesn't understand.
    <tscreen><verb>
	dd if=/dev/zero of=/dev/rsd1 bs=1k count=1
	disklabel -Brw sd1 auto
	disklabel -e sd1				# create the `e' partition
	newfs -d0 /dev/rsd1e
	mkdir -p /1
	vi /etc/fstab					# add an entry for /dev/sd1e
	mount /1
    </verb></tscreen>

	An alternate method is:
	
    <tscreen><verb>
	dd if=/dev/zero of=/dev/rsd1 count=2
	disklabel /dev/rsd1 | disklabel -BrR sd1 /dev/stdin
	newfs /dev/rsd1e
	mkdir -p /1
	vi /etc/fstab					# add an entry for /dev/sd1e
	mount /1
    </verb></tscreen>


    <sect><heading> * Non-traditional Drives</heading>
    <sect1><heading> * Zip Drives</heading>
    <sect1><heading> * Jazz Drives</heading>
    <sect1><heading> * Sequest Drives</heading>