5.12. Allocating disk space
5.12.1. Partitioning schemes
When it comes to partitioning your machine,
there is no universally correct way to do it. There are
many factors that must be taken into account depending on
the purpose of the machine.
For a simple workstation with limited disk space, such
as a laptop, you may have as few a 3 partitions. A partition for
/, /boot, and swap.
However, for most users this is not a recommended solution.
The traditional way is to have a (relatively) small
root filesystem, and separate partitions for filesystems such as
/usr and /home>.
Creating a separate root filesystem if the root filesystem is small and
not heavily used, it is less likely to become corrupt when the system
crashes, and therefore make it easier to recover a crashed system. The
reason is to prevent having the root filesystem get filled and cause a
When creating your partitioning scheme, there are some things you
need to remember. You cannot create separate partitions for the following
directories: /bin, /etc,
/lib, and /sbin. The
contents of these directories are required at bootup and must
always be part of the / partition.
It is also recommended that you create separate partitions for
/var and /tmp. This is
because both directories typically have data that is constantly
changing. Not creating separate partitions for these filesystems
puts you at risk of having log file fill up our /
An example of a server partition is:
Filesystem Size Used Avail Use% Mounted on
/dev/hda2 9.7G 1.3G 8.0G 14% /
/dev/hda1 128M 44M 82M 34% /boot
/dev/hda3 4.9G 4.0G 670M 86% /usr
/dev/hda5 4.9G 2.1G 2.5G 46% /var
/dev/hda7 31G 24G 5.6G 81% /home
/dev/hda8 4.9G 2.0G 670M 43% /opt
The problem with having many partitions is that it splits
the total amount of free disk space into many small pieces. One way
to avoid this problem is to use to create Logical Volumes.
5.12.2. Logical Volume Manager (LVM)
Using LVM allows administrators the flexibility to create
logical disks that can be expanded dynamically as more disk space
This is done first by creating partitions with as an
0x8e Linux LVM partition type. Then the Physical Partitions
are added to a Volume Group and
broken up into chunks, or Physical Extents
Volume Group. These extends can then be grouped
into Logical Volumes. These Logical Volumes
then can be formatted just like a physical partition. The big
difference is that they can be expanded by adding more extents to
Right now, a full discussion of LVM is beyond the scope of this
guide. However, and excellent resource for learning more about LVM
can be found at https://www.tldp.org/HOWTO/LVM-HOWTO.html.
5.12.3. Space requirements
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.
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.
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, a 345 MB hard disk
is really a 330 MB hard disk.
Swap space allocation is discussed in Section 6.5.
5.12.4. Examples of hard disk allocation
I used to have a 10 GB hard disk. Now I am using a 30 GB
hard disk. I'll explain how and why I partitioned those
First, I created a /boot partition
at 128 MG. This is larger than I will need, and big enough to
give me space if I need it. I created a separate
/boot partition to ensure that this
filesystem will never get filled up, and therefore will be
bootable. Then I created a 5 GB /var
partition. Since the /var filesystem is
where log files and email is stored I wanted to isolate it
from my root partition. (I have had log files grow overnight
and fill my root filesystem in the past.) Next, I created a 15 GB
/home partition. This is handy in the event
of a system crash. If I ever have to re-install Linux from scratch,
I can tell the installation program to not format this partition, and
instead remount it without the data being lost. Finally
since I had 512 MG of RAM I created a 1024 MG (or 1 GB) swap
partition. This left me with roughly a 9 GB root filesystem. I using
my old 10 GB hard drive, I created an 8 GB /usr
partition and left 2 GB unused. This is incase I need more space
in the future.
In the end, my partition tables looked like this:
Table 5-3. My Partitions
|9 GB||root filesystem|
|1 GB||swap partition|
| 8 GB||/usr
| 2 GB||scratch partition|
5.12.5. Adding more disk space for Linux
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 /etc/fstab
so that it is mounted automatically.
5.12.6. Tips for saving disk space
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.
If you cannot uninstall packages, you might look into
compression. Compression programs such as gzip
will compress (and uncompress)
individual files or groups of files. The gzexe
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
or DriveSpace for Windows, the principle is the same.)
Another way to save space is to take special care when
formatting you partitions. Most modern filesystems will allow
you to specify the block size. The block size is chunk size that
the filesystem will use to read and write data. Larger block sizes
will help disk I/O performance when using large files, such as databases.
This happens because the disk can read or write data for a longer
period of time before having to search for the next block. The