Linux with Operating System Concepts

logical volume manager
. This is a means of implementing one or more disk 
partitions in a logical rather than physical way so that partitions can be easily resized. This 
means that part of the file system is managed by software. The software specifically keeps 
track of the partitions’ file usage so that it can modify the “boundaries” of the partitions. 
FIGURE 8.9 
Default partitions.

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This allows you to have an adaptable set of partitions whereby they grow as needed. Using 
physical disk partitions, you are locked into the established size of the partitions. If you 
make a partition too small, you might find that you do not have enough disk space for 
Linux to run at all, or at least to run effectively. Or, you might find that you have run out of 
space and you have to delete files. At the other extreme, if one partition is too large, then 
other partitions might eventually suffer from too small a size. Now, these other partitions 
may fill up more quickly than desired. Resizing or otherwise changing partitions requires 
making physical changes to the disk that has the potential of destroying data. We examine 
LVM in more detail in Chapter 10.
Let us imagine that we do not want to use this default setup of partitions and want to 
create instead partitions for / (root), /var, and /home. These are 
mount points
that provide 
an entry to the partition from the root file system. That is, the mount point is the logical 
location as we reference it from the operating system. All these partitions will be managed 
by LVM so that we can ensure that as they grow, as long as there is disk space available, the 
partitions will not run out of space. First, we need to delete the current setup. Select the two 
rows of lv_root and lv_swap (one at a time) and select the Delete button. You would wind 
up with a single entry underneath VolGroup that says Free followed by the amount of free 
space (9736 in this case).
Now, we can create our new partitions. Click on Create and you will see the Create Storage 
window as shown in Figure 8.10. You would select LVM Logical Volume underneath the 
FIGURE 8.10 
Creating a partition.

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Create LVM section and then select the appropriate Volume Group (VolGroup is the only 
one available in our example).
Clicking on the Create button from this pop-up window presents you with two new 
pop-up windows, as shown in Figure 8.11. In the Make Logical Volume window, select the 
Mount Point, File System Type, and Size. By default, you are provided ext4 for the type, 
which is the best choice. Mount Point for our first partition will be / (root) and we will use 
a size sufficient for / to leave us space for other partitions. A size of 4000 MB is satisfactory. 
With this filled in, click on OK and both windows disappear leaving us with two entries 
under VolGroup, LogVol00 whose size is 4000 MB, whose mount point is / and whose type 
is ext4, and Free which is now 5736. We repeat this process to create /var (in this case, we 
will give /var 4000 MB).
For the swap space, instead of selecting a mount point, we select under File System Type 
“swap”. Swap does not have a mount point, so the Mount Point selection becomes Applicable>. Here, we select a size of 2000 MB because we are limited based on the size of 
the virtual machine (10 G). The common size for swap space is often cited as 1–2 times that 
of main memory. However, Linux is a very efficient operating system and you may never 
need more than about 2 GB worth of swap space. Our last partition has a mount point of 
/home and will use the remaining space, 736. Note that we could have chosen to encrypt 
any of these file systems during this partitioning.
At this point, we would have the following list of partitions specified:
LVM Volume Groups
VolGroup 
9736
LogVol03
736 /home ext4
LogVol01 4000 /var ext4
LogVol00 4000 / 
ext4
LogVol02 1000
swap
FIGURE 8.11 
Creating logical partitions.

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Hard Drives
sda
sda1 
500 
/boot 
ext4
sda2 9739 VolGroup
physical volume (LVM)
This summary tells us that our physical hard disk is divided into two file systems, sda1 
and sda2 that is storing the boot partition (/boot) and VolGroup, an LVM. VolGroup itself 
consists of four logical groups, /, /home, /var, and swap that has no mount point. We can 
now proceed with formatting our disk with the above layout. Click on Next and a Format 
Warnings pop-up window appears. Click Format and then a Writing storage configuration 
to disk-warning window appears and click on Write changes to disk. A number of win-
dows appear indicating the formatting and creation of the file systems as specified. Now, 
we can continue with the installation.
The main advantage of LVM is that a partition is not restricted to the size specified when 
we formatted the disk. Instead, a partition grows by grabbing space from the available disk, 
sda2 in this case, as needed and as available. Only if sda2 runs out of space would a parti-
tion not be able to grow further. By using the LVM, we, for instance, could potentially use 
more space for /home than the 736 MB specified while using less space for say /var.
However, the flexibility from LVM comes with some costs. One reason why you might 
want to forego the use of an LVM is that it adds a layer of complexity to the file system, 
resulting in both a reduction in efficient access and a complication with processes such as 
system booting and disaster recovery. Again, refer to Chapter 10 for a greater discussion 
on LVM.
In the meantime though, let us look at creating partitions with physical sizes by 
using the Standard Partition selection from the Create Storage window. With this selec-
tion, we get an Add Partition window rather than a Make Logical Volume window. See 
Figure 8.12.
In creating our own physical partitions, we specify much of the same information as 
we did with the LVM approach. We need to specify the mount point, file system type, 
and size. For the size specification, we can provide the size in the Size box that indicates 
a fixed size, we can select Fill all space up to and then specify a maximum size, or we can 
select Fill to maximize allowable size that uses the remainder of this drive’s free space. You 
can also select whether this partition will be a primary partition and whether it should be 
encrypted. A primary partition is one with a boot program stored in it. We use a similar set 
of partitions as we did earlier except that we will forego a separate /boot partition, instead 
placing /boot with the root partition (/). Here are the values we might select:
• Partition 1: / (mount point), ext4 (type), 4000 MB, Fixed Size
• Partition 2: /var, ext4, 4000 MB, Fixed Size
• Partition 3: (mount point), swap, 2000 MB, Fixed Size
• Partition 4: /home, ext4, Fill to maximum size

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As before, swap space does not have a mount point. All the other partitions have mount 
points.
Before partitioning your hard disk, you need to consider what you are going to use your 
computer for and make a wise choice. Once partitioned, while it is possible to repartition 
or resize your partitions, it is not necessarily a good thing to do given that you can easily 
destroy data in the process. We examine the file system and partitioning in more detail in 
Chapter 10. For now, we will continue with our installation.
With your partition information filled out, select Next. Two pop-up windows will 
appear consecutively. The first warns you that the changes you are making will delete data, 
click on Format. The second states that you are writing configuration information to the 
disk. Select Write changes to the disk. You will then see formatting taking place on /dev/
sda (or /dev/hda) as the partitions are created.
The next window allows you to specify the location of the boot loader program and 
the boot image(s) of your operating system. For our first partition using LVM, /boot was 
explicitly placed on /dev/sda1. Without using LVM, the /boot directory is located on the 
root (/) partition that is again placed on /dev/sda1. You should not have to do anything 
with the bootloader specification as the default settings should be correct. You can also 
establish a boot loader password if desired. Click Next to continue.
8.3.3 Finishing Your Installation
We have reached the last screen before installation finally begins. We must specify the type 
of installation. The type of installation dictates the software to be installed. Your choices are 
Desktop that provides access to the GUI, Minimal Desktop that provides only some GUI 
facilities, Minimal that provides only text-based access (and is the default), Basic Server, 
Database Server, Web Server, Virtual Host, and Software Development Workstation. The 
FIGURE 8.12 
Creating a partition.

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last five categories cause different application software to be loaded. If you were intending 
your computer to be used for one of these latter categories, you do not necessarily have to 
select it now as you could install the software later (see Chapter 13). You can also add addi-
tional software packages on this page. The default is to “Customize later.” Select Desktop 
and then Next. At this point, CentOS 6 is unpacked and installed. Depending on the speed 
of your processor, hard disk, and optical drive, this will take several minutes, perhaps as 
many as 20. The last step after installation is to reboot your computer (the VM).
Upon rebooting, you will see a welcome screen. From here, you are nearly done with the 
installation. First, you will have to agree to the license. In this case, it is the CentOS license 
under the GPL. The license states that CentOS 6 comes with no guarantees or warranties 
and also states that individual software packages will come with their own licenses.
At the next window, you are required to provide your first user’s account. It is important 
to create this first user account so that, when you are to log in for the first time, you log in as 
a user and not as root. Logging in as root through the GUI is never advisable because you 
have control over all files in the file space and so it is too easy to delete or destroy data acci-
dentally. For the first user’s account, you will provide the username, the user’s full name, 
and the user’s initial password. As with the root password, this password will be tested to 
see if it is a strong password, and if not, you will be warned. You can also select a network 
login mechanism. The Advanced… button will bring up the User Manager window, which 
we will explore in Chapter 9.
The next window allows you to set the date and time or alternatively synchronize this 
over the network. Finally, the last window provides you the ability to establish the kdump 
kernel-dumping mechanism including whether kdump should be enabled, the size of the 
dump, and the kdump configuration file. Alternatively, you can leave it disabled or not 
alter the default. After completing this step, you are provided with the CentOS 6 GUI login 
screen and you are done! Log in and start using Linux.
Although you now have a desktop available, you will probably find that there are a num-
ber of additional configuration steps required. These include, at a minimum, the creation of 
user accounts (we cover this in Chapter 9), the installation of additional software (we cover 
this in Chapter 13), and ensuring that your network is configured correctly (we cover this 
in Chapter 12). Other aspects of configuring your Linux environment include establishing 
and configuring services (covered in Chapter 11), setting up scripts to automate tasks such 
as backups, and setting up proper security such as the firewall (also covered in Chapter 12).
8.4 INSTALLING UBUNTU
Ubuntu is a descendant of Debian Linux. Here, we discuss the installation of Ubuntu 12. 
As with the CentOS install, much of it is simplified. The start-up window asks if you want 
to try Ubuntu (via the Live or bootable CD) or install. You would select Install and the 
language of choice (English is the default). See Figure 8.13.
You are cautioned that you should have at least 4.5 GB of available hard-drive space and 
Internet access. You can install updates during the installation as well as install third-party 
software. You are then asked whether to erase the hard disk and install Ubuntu, or cre-
ate a separate partition for Ubuntu to the current disk setup (you can also resize existing 

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Ubuntu partitions). Unless you specify the latter, you will be given the default Ubuntu