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<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN">
<HTML
><HEAD
><TITLE
>Allocating disk space</TITLE
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><HR
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WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1384"
>Allocating disk space</A
></H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1386"
>Partitioning schemes</A
></H2
><P
>It is not easy to partition a disk in the best possible way.
Worse, there is no universally correct way to do it; there are
too many factors involved.</P
><P
>The traditional way is to have a (relatively) small
root filesystem, which contains <TT
CLASS="FILENAME"
>/bin</TT
>,
<TT
CLASS="FILENAME"
>/etc</TT
>, <TT
CLASS="FILENAME"
>/dev</TT
>,
<TT
CLASS="FILENAME"
>/lib</TT
>, <TT
CLASS="FILENAME"
>/tmp</TT
>, and other
stuff that is needed to get the system up and running. This way,
the root filesystem (in its own partition or on its own disk)
is all that is needed to bring up the system. The reasoning is
that if the root filesystem is small and is not heavily used,
it is less likely to become corrupt when the system crashes, and
you will therefore find it easier to fix any problems caused by
the crash. Then you create separate partitions or use separate
disks for the directory tree below <TT
CLASS="FILENAME"
>/usr</TT
>, the
users' home directories (often under <TT
CLASS="FILENAME"
>/home</TT
>),
and the swap space. Separating the home directories (with the
users' files) in their own partition makes backups easier, since
it is usually not necessary to backup programs (which reside
below <TT
CLASS="FILENAME"
>/usr</TT
>). In a networked environment it
is also possible to share <TT
CLASS="FILENAME"
>/usr</TT
> among several
machines (e.g., by using NFS), thereby reducing the total disk
space required by several tens or hundreds of megabytes times
the number of machines.</P
><P
>The problem with having many partitions is that it splits
the total amount of free disk space into many small pieces.
Nowadays, when disks and (hopefully) operating systems are
more reliable, many people prefer to have just one partition
that holds all their files. On the other hand, it can be less
painful to back up (and restore) a small partition.</P
><P
>For a small hard disk (assuming you don't do kernel
development), the best way to go is probably to have just one
partition. For large hard disks, it is probably
better to have a few large partitions, just in case
something does go wrong. (Note that `small' and `large' are
used in a relative sense here; your needs for disk space
decide what the threshold is.)</P
><P
>If you have several disks, you might wish to have the
root filesystem (including <TT
CLASS="FILENAME"
>/usr</TT
>) on one,
and the users' home directories on another.</P
><P
>It is a good idea to be prepared to experiment a bit
with different partitioning schemes (over time, not just
while first installing the system). This is a bit of work,
since it essentially requires you to install the system from
scratch several times, but it is the only way to be sure you do
it right.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1404"
>Space requirements</A
></H2
><P
>The Linux distribution you install will give some indication
of how much disk space you need for various configurations.
Programs installed separately may also do the same. This will
help you plan your disk space usage, but you should prepare
for the future and reserve some extra space for things you will
notice later that you need.</P
><P
>The amount you need for user files depends on what your
users wish to do. Most people seem to need as much space for
their files as possible, but the amount they will live happily
with varies a lot. Some people do only light text processing
and will survive nicely with a few megabytes, others do heavy
image processing and will need gigabytes.</P
><P
>By the way, when comparing file sizes given in
kilobytes or megabytes and disk space given in megabytes, it
can be important to know that the two units can be different.
Some disk manufacturers like to pretend that a kilobyte is 1000
bytes and a megabyte is 1000 kilobytes, while all the rest of
the computing world uses 1024 for both factors. Therefore,
my 345 MB hard disk was really a 330 MB hard disk.
<A
NAME="AEN1409"
HREF="#FTN.AEN1409"
>[1]</A
>
</P
><P
>Swap space allocation is discussed in <A
HREF="x1532.html"
>the section called <I
>Allocating swap space</I
> in Chapter 5</A
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1413"
>Examples of hard disk allocation</A
></H2
><P
>I used to have a 109 MB hard disk. Now I am using a 330 MB
hard disk. I'll explain how and why I partitioned these
disks.</P
><P
>The 109 MB disk I partitioned in a lot of ways, when my
needs and the operating systems I used changed; I'll explain
two typical scenarios. First, I used to run MS-DOS together
with Linux. For that, I needed about 20 MB of hard disk, or
just enough to have MS-DOS, a C compiler, an editor, a few other
utilities, the program I was working on, and enough free disk
space to not feel claustrophobic. For Linux, I had a 10 MB swap
partition, and the rest, or 79 MB, was a single partition with all
the files I had under Linux. I experimented with having separate
root, <TT
CLASS="FILENAME"
>/usr</TT
>, and <TT
CLASS="FILENAME"
>/home</TT
>
partitions, but there was never enough free disk space in one
piece to do much interesting.</P
><P
>When I didn't need MS-DOS anymore, I repartitioned the
disk so that I had a 12 MB swap partition, and again had the
rest as a single filesystem.</P
><P
>The 330 MB disk is partitioned into several partitions, like
this:
<DIV
CLASS="INFORMALTABLE"
><P
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>5 MB</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>root filesystem</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
> 10 MB</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>swap partition</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>180 MB</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>\fn{/usr} filesystem</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>120 MB</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>\fn{/home} filesystem</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
> 15 MB</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>scratch partition</TD
></TR
></TABLE
><P
></P
></DIV
>
The scratch partition is for playing around with things that
require their own partition, e.g., trying different Linux
distributions, or comparing speeds of filesystems. When not
needed for anything else, it is used as swap space (I like to
have a lot of open windows).</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1439"
>Adding more disk space for Linux</A
></H2
><P
>Adding more disk space for Linux is easy, at least after the
hardware has been properly installed (the hardware installation
is outside the scope of this book). You format it if necessary,
then create the partitions and filesystem as described above,
and add the proper lines to <TT
CLASS="FILENAME"
>/etc/fstab</TT
>
so that it is mounted automatically.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1443"
>Tips for saving disk space</A
></H2
><P
>The best tip for saving disk space is to avoid installing
unnecessary programs. Most Linux distributions have an
option to install only part of the packages they contain,
and by analyzing your needs you might notice that you don't
need most of them. This will help save a lot of disk space,
since many programs are quite large. Even if you do need a
particular package or program, you might not need all of it.
For example, some on-line documentation might be unnecessary,
as might some of the Elisp files for GNU Emacs, some of the
fonts for X11, or some of the libraries for programming.</P
><P
>If you cannot uninstall packages, you might look into
compression. Compression programs such as <B
CLASS="COMMAND"
>gzip</B
>
or <B
CLASS="COMMAND"
>zip</B
> will compress (and uncompress)
individual files or groups of files. The <B
CLASS="COMMAND"
>gzexe</B
>
system will compress and uncompress programs invisibly to the
user (unused programs are compressed, then uncompressed as they
are used). The experimental DouBle system will compress all
files in a filesystem, invisibly to the programs that use them.
(If you are familiar with products such as Stacker for MS-DOS,
the principle is the same.)</P
></DIV
></DIV
><H3
>Notes</H3
><TABLE
BORDER="0"
CLASS="FOOTNOTES"
WIDTH="100%"
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1409"
HREF="x1384.html#AEN1409"
>[1]</A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Sic transit discus mundi.</P
></TD
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