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154 lines
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<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<TITLE>2.2.3 Linux partition requirements</TITLE>
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<meta name="description" value="2.2.3 Linux partition requirements">
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<BR> <HR><A NAME=tex2html2561 HREF="node69.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html2559 HREF="node65.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html2553 HREF="node67.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html2563 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html2564 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html2562 HREF="node69.html">2.2.4 Repartitioning your drives</A>
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<B>Up:</B> <A NAME=tex2html2560 HREF="node65.html">2.2 Preparing to Install </A>
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<B> Previous:</B> <A NAME=tex2html2554 HREF="node67.html">2.2.2 Repartitioning concepts</A>
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<BR> <HR> <P>
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<H2><A NAME=SECTION00423000000000000000>2.2.3 Linux partition requirements</A></H2>
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<P>
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<A NAME=secinstallswap> </A>
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<A NAME=secinstalllinuxreqs> </A>
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<P>
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Before we explain how to repartition your drives, you need to have an
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idea of how much space you will be allocating for Linux. We will be
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discussing how to create these partitions later, in
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Section <A HREF="node73.html#secinstalllinuxfdisk">2.3.3</A>.
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<P>
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On UNIX systems, files are stored on a <b>filesystem</b>, which is
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<A NAME=1022> </A>
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essentially a section of the hard drive (or other medium, such as CD-ROM
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or diskette) formatted to hold files. Each filesystem is associated with
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a specific part of the directory tree; for example, on many systems,
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there is a filesystem for all of the files in the directory <tt>/usr</tt>, another
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for <tt>/tmp</tt>, and so on. The <b>root filesystem</b> is the primary
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filesystem, which corresponds to the topmost directory, <tt>/</tt>.
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<A NAME=1027> </A>
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<A NAME=1028> </A>
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<P>
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Under Linux, each filesystem lives on a separate partition on the hard
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drive. For instance, if you have a filesystem for <tt>/</tt> and another
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for <tt>/usr</tt>, you will need two partitions to hold
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the two filesystems.
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<P>
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Before you install Linux, you will need to prepare filesystems for
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storing the Linux software. You must have at least one filesystem (the
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root filesystem), and therefore one partition, allocated to Linux.
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Many Linux users opt to store all of their files on the root filesystem,
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which is in most cases easier to manage than several filesystems and
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partitions.
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<P>
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However, you may create multiple filesystems for Linux if
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you wish---for example, you may want to use separate filesystems for
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<tt>/usr</tt> and <tt>/home</tt>. Those readers with UNIX system administration
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experience will know how to use multiple filesystems creatively. In
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Chapter <A HREF="node155.html#chapsysadmnum">4</A> we discuss the use of multiple partitions
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and filesystems.
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<P>
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<A NAME=1034> </A>
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Why use more than one filesystem? The most commonly stated reason is
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safety; if, for some reason, one of your filesystems is damaged,
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the others will (usually) be unharmed. On the other hand, if you store
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all of your files on the root filesystem, and for some reason the
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filesystem is damaged, then you may lose all of your files in one fell
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swoop. This is, however, rather uncommon; if you backup the system
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regularly you should be quite safe.<A NAME=tex2html239 HREF="footnode.html#1035"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>
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<P>
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Another reason to use multiple filesystems is to divvy up storage between
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multiple hard drives. If you have, say, 40 megabytes free on one hard drive,
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and 50 megabytes free on another, you might want to create a 40-megabyte root
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filesystem on the first drive and a 50-megabyte <tt>/usr</tt> filesystem on the
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other. Currently it is not possible for a single filesystem to span multiple
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drives; if your free hard drive storage is fragmented between drives you
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will need to use multiple filesystems to utilize it all.
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<P>
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<A NAME=1037> </A>
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In summary, Linux requires at least one partition, for the root filesystem.
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If you wish to create multiple filesystems, you will need a separate
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partition for each additional filesystem. Some distributions of Linux
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automatically create partitions and filesystems for you, so you may not need
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to worry about these issues at all.
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<P>
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Another issue to consider when planning your partitions is swap space.
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<A NAME=1038> </A>
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If you wish to use swap space with Linux, you have two options. The
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first is to use a <em>swap file</em> which exists on one of your Linux
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filesystems. You will create the swap file for use as virtual RAM after
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you install the software. The second option is to create a
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<em>swap partition</em>, an individual partition to be used only as swap
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space. Most people use a swap partition instead of a swap file.
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<A NAME=1041> </A>
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<P>
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A single swap file or partition may be up to 16 megabytes in size. If
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you wish to use more than 16 megabytes of swap, you can create multiple
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swap partitions or files---up to eight in all. For example, if you need
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32 megabytes of swap, you can create two 16-megabyte swap partitions.
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<P>
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Setting up a swap partition is covered in
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Section <A HREF="node74.html#secinstalllinuxmkswap">2.3.4</A>, and setting up a swap file in
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Chapter <A HREF="node155.html#chapsysadmnum">4</A>.
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<P>
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Therefore, in general, you will create at least two partitions for Linux:
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one for use as the root filesystem, and the other for use as swap space.
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There are, of course, many variations on the above, but this is the
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minimal setup. You are not required to use swap space with Linux, but if
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you have less than 16 megabytes of physical RAM it is strongly
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suggested that you do.
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<P>
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Of course, you need to be aware of how much <em>space</em> these partitions
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will require. The size of your Linux filesystems (containing the software
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itself) depends greatly on how much software you're installing and
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what distribution of Linux you are using. Hopefully, the documentation
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that came with your distribution will give you an approximation of the
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space requirements. A small Linux system can use 20 megabytes or less; a
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larger system anywhere from 80 to 100 megabytes, or more. Keep in mind that
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in addition to the space required by the software itself, you need to
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allocate extra space for user directories, room for future expansion, and
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so forth.
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<P>
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<A NAME=1045> </A>
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The size of your swap partition (should you elect to use one) depends on
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how much virtual RAM you require. A rule of thumb is to use a swap partition
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that is twice the space of your physical RAM; for example, if you have 4
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megabytes of physical RAM, an 8-megabyte swap partition should suffice.
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Of course, this is mere speculation---the actual amount of swap space
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that you require depends on the software which you will be running. If you
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have a great deal of physical RAM (say, sixteen megabytes or more), you
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may not wish to use swap space at all.
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<P>
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<b>Important note:</b> Because of BIOS limitations, it is usually not
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possible to boot
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from partitions using cylinders numbered over 1023. Therefore, when
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setting aside space for Linux, keep in mind that you may not want to use
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a partition in the <b>></b>1023-cylinder range for your Linux root filesystem.
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Linux can still <em>use</em> partitions with cylinders numbered over
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1023, however, you may not be able to <em>boot</em> Linux from such a
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partition. This advice may seem premature, but it is important to
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know while planning your drive layout.
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<P>
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If you absolutely must use a partition with cylinders numbered over
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1023 for your Linux root filesystem, you can always boot Linux from floppy.
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This is not so bad, actually---it only takes a few seconds longer to boot
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than from the hard drive. At any rate, it's always an option.
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<P>
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<BR> <HR><A NAME=tex2html2561 HREF="node69.html"><IMG ALIGN=BOTTOM ALT="next" SRC="next_motif.gif"></A> <A NAME=tex2html2559 HREF="node65.html"><IMG ALIGN=BOTTOM ALT="up" SRC="up_motif.gif"></A> <A NAME=tex2html2553 HREF="node67.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="previous_motif.gif"></A> <A NAME=tex2html2563 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <A NAME=tex2html2564 HREF="node250.html"><IMG ALIGN=BOTTOM ALT="index" SRC="index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html2562 HREF="node69.html">2.2.4 Repartitioning your drives</A>
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<B>Up:</B> <A NAME=tex2html2560 HREF="node65.html">2.2 Preparing to Install </A>
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<B> Previous:</B> <A NAME=tex2html2554 HREF="node67.html">2.2.2 Repartitioning concepts</A>
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<BR> <HR> <P>
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<BR> <HR>
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<P><ADDRESS>
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<I>Matt Welsh <BR>
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mdw@sunsite.unc.edu</I>
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</ADDRESS>
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