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Chapter 4
IMPLEMENTATION
The implementation phase of any project development is the most important phase as it yields
the final solution, which solves the problem at hand. The implementation phase involves the
actual materialization of the ideas, which are expressed in the analysis document and developed
in the design phase.
We have implemented rejuvenation on three domain OS, VM, VMM using warm migration and
cold rejuvenation methods, based on Time and Prediction based rejuvenation policies. We also
simulate the rejuvenation of these failing nodes. We have implemented petri-net modeling into
our project.
4.1 Platform Selection:
4.1.1 KVM/QEMU:
KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware
containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel
module, kvm.ko that provides the core virtualization infrastructure and a processor specific
module, kvm-intel.ko or kvm-amd.ko. KVM also requires a modified QEMU although work is
underway to get the required changes upstream.
Using KVM, one can run multiple virtual machines running unmodified Linux or Windows
images. Each virtual machine has private virtualized hardware: a network card, disk, graphics
adapter, etc.
The kernel component of KVM is included in mainline Linux, as of 2.6.20.KVM is open source
software. A wide variety of guest operating systems work with KVM, including many flavours
of Linux, BSD, Solaris, Windows, Haiku,ReactOS, Plan 9, and AROS Research Operating
System. In addition Android 2.2, GNU/Hurd (Debian K16), Minix 3.1.2a, Solaris 10 U3, Darwin

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8.0.1 and more OSs and some newer versions of these with limitations are known to work. A
modified version of QEMU can use KVM to run Mac OS X.
4.1.2 SPNP (Stochastic Petri Net Package):
This package was developed by Ciardo et.al. The model type used for input is a stochastic
reward net (SRN). SRNs incorporate several structural extensions to GSPNs such as marking
dependencies (marking dependent arc cardinalities, guards, etc.) and allow reward rates to be
associated with each marking. The reward function can be marking dependent as well.
They are specified using CSPL (C based SRN Language) which is an extension of the C
programing language with additional constructs for describing the SRN models. SRN
specifications are automatically converted into a Markov reward model which is then solved to
compute a variety of transient, steady-state, cumulative, and sensitivity measures. For SRNs with
absorbing markings, mean time to absorption and expected accumulated reward until absorption
can be computed.
The interface increases the power of SPNP (the Stochastic Petri Net Package) by providing a
means of rapidly developing stochastic reward nets (SRNs); the model type used for input. Input
to SPNP is specified using CSPL (C based SPN Language), but the interface removes this burden
from the user by providing an interface for graphical representation of the model.
The first interface was implemented with Tcl/Tk. Then JAVA was used to have to develop the
new version, which makes the look and feel of the interface.
4.2 Programming Language Used (Language Selection):
C is a general-purpose programming language initially developed by Dennis Ritchie . C is
an imperative (procedural) language. It was designed to be compiled using a relatively
straightforward compiler, to provide low-level access to memory, to provide language constructs
that map efficiently to machine instructions, and to require minimal run-time support. C was
therefore useful for many applications that had formerly been coded inassembly language, such
as in system programming.

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Despite its low-level capabilities, the language was designed to encourage cross-
platform programming. A standards-compliant and portably written C program can be compiled
for a very wide variety of computer platforms and operating systems with few changes to its
source code. The language has become available on a very wide range of platforms, from
embedded microcontrollers to supercomputers.
Header Name Description
Stdio.h Defines standard buffered input/output
Stdlib.h Defines numeric conversion functions, pseudo-
random numbers generation functions, memory
allocation, process control functions
String.h Defines string handling functions.
Ctype.h Defines set of functions used to classify
characters by their types or to convert between
upper and lower case in a way that is
independent of the used character set
Locale.h Defines localization functions.
Sys/time.h Defines date and time handling functions
Unistd.h Defines standard symbolic constants and types
Fcntl.h Defines the following requests and arguments
for use by the functions fcntl() and open().
Values for cmd used by fcntl()

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4.2 CentOS (OS selection)
The CentOS Linux distribution is a stable, predictable, manageable and reproducible platform
derived from the sources of Red Hat Enterprise Linux (RHEL). The process delivered has a clear
governance model, increased transparency and access.
Since March 2004, CentOS Linux has been a community-supported distribution derived from
sources freely provided to the public by Red Hat. As such, CentOS Linux aims to be functionally
compatible with RHEL. CentOS change packages to remove upstream vendor branding and
artwork. CentOS Linux is no-cost and free to redistribute.
CentOS Linux is developed by a small but growing team of core developers. In turn the core
developers are supported by an active user community including system administrators, network
administrators, managers, core Linux contributors, and Linux enthusiasts from around the world.
We opt this OS because it is highly compatible and stable , it is very easy to install KVM and
configure it .moreover configuring NFS is easy for beginners and ports can be resolved properly.
The forums of this OS had all the solutions to problems we have faced in other OS like Ubuntu,
fedora. Moreover it is open source and codes are available online
4.3 Installing and configuring KVM on cent OS
4.3.1 Check Hardware Virtualization support
KVM requires hardware virtualization support such as Intel VT or AMD's AMD-V,
which are instruction set extensions for hardware-assisted virtualization. Check if
hardware virtualization support is available on CentOS host machine:
$ egrep -i 'vmx|svm' --color=always /proc/cpuinfo
If CPU flags contain "vmx" or "svm", it means hardware virtualization support is
available.

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4.3.2 Configure FQDN for local host
Configure FQDN (fully qualified domain name) for local host. Otherwise, you may get
warnings while launching libvirtd daemon such as "getaddrinfo failed for 'myhost': Name
or service not known".
To configure FQDN, edit the following configuration file:
$ sudo -e /etc/sysconfig/network
HOSTNAME=xxx.yyy
4.3.2.1 Disable SELinux
Before installing KVM, be aware that there are several SELinux Booleans that can
affect the behavior of KVM and libvirt. In this tutorial, I'm going to set SELinux to
0"Permissive" for demonstration purpose. If you do not wish to change SELinux
mode.
To disable SELinux on CentOS:
$sudo -e /etc/selinux/config
SELINUX=permissive
4.3.2.2 Reboot the machine for the change to take effect.
4.4Install KVM, QEMU and user-space tools
4.4.1 Install KVM and virtinst (a tool to create VMs) as follows:
$sudo yum install kvm libvirt python-virtinst qemu-kvm
4.4.2 Start libvirtd daemon, and set it to auto-start:
$sudo service libvirtd start
$sudo chkconfig libvirtd on
4.4.3 Check if KVM has successfully been installed. You should see no error as follows.

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$ sudo virsh -c qemu:///system list
Id Name State
----------------------------------------------------
4.4.4 Configure Linux Bridge for VM Networking
Installing KVM alone does not allow VMs to communicate with each other or access
external networks. You need to configure VM networking separately. In this tutorial, I
am going to set up "bridged networking" via Linux bridge.
 Install a package needed to create and manage bridge devices:
$sudo yum install bridge-utils
 Disable Network Manager service if it's enabled, and switch to default net
manager as follows.
$sudo service NetworkManager stop
$sudo chkconfig NetworkManager off
$sudo chkconfig network on
$sudo service network start
To configure a new bridge, you have to pick an active network interface (e.g.,
eth0), and enslave it to the bridge. Depending on whether the network interface is
assigned an IP address via DHCP or statically, there are two different ways to
configure a new bridge.
 To configure bridge br0 via DHCP:
$sudo -e /etc/sysconfig/network-scripts/ifcfg-eth0
 Modify the file ifcfg-etho as shown below:
DEVICE=eth0

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TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BRIDGE=br0
$sudo -e /etc/sysconfig/network-scripts/ifcfg-br0
 Modify the file ifcfg-br0 as shown below:
DEVICE=br0
NM_CONTROLLED=yes
ONBOOT=yes
TYPE=Bridge
BOOTPROTO=dhcp
 Once configuration files are generated accordingly, run the following to
activate the change.
$sudo service network restart
 You should now see br0 bridge interface with a proper IP address as
follows.
$ifconfig
4.4.5 Install VirtManager
The final step is to install a desktop UI called VirtManager for managing virtual
machines (VMs) through libvirt.
To install VirtManager:
$ sudo yum install virt-manager libvirt qemu-system-x86 openssh-askpass libcanberra-
devel
4.5 Setup a minimal CentOS 6 NFS configuration
4.5.1 SERVER CONFIGURATION:
 To setup the server: 172.16.30.48/255.255.255.254

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 Before setup the server system needs update the packages:
"yum update"
 Once update is completed reboot the system.
"shutdown -r now"
 Install nfs-utils rpcbind system configuration package.
"yum install nfs-utils rpcbind system-config-firewall-tui"
 Modify the selinux file to disable SELINUX
"vi /etc/sysconfig/selinux" and set "SELINUX=disabled".
"setenforce 0"
 Make a folder to be shared. eg:
$ mkdir /var/lib/libvirt/images
 Do the following:
$ chkconfig nfs on
$ chkconfig nfslock on
$ chkconfig rpcbind on
 Configure the firewall setting:
$ "system-config-firewall-tui"
 Modify the exports file to add the shared storage to make live migration from
source to destination system

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/var/lib/libvirt/images 172.16.30.48/255.255.255.254 (rw,
sync, no_root_squash)
 Modify the hosts.allow file by following lines:
$ sudo /etc/hosts.allow
mountd: 172.16.30.46/255.255.255.254
 Modify the hosts.deny file by following lines
portmap:ALL
lockd:ALL
mountd:ALL
rquotad:ALL
statd:ALL
 Restart the following services on Server machine once you completed all the above
steps:
$ sudo service rpcbind restart
$ sudo service nfs restart
$ sudo service nfslock restart

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CLIENT CONFIGURATION:
 To Setup The Client: 172.16.30.46/255.255.255.254
 Before setup the client system needs update the packages:
$ sudo yum update
 Once update is completed reboot the system.
$ sudo shutdown -r now
 Install nfs-utils rpcbind system configuration package.
$ sudo yum install nfs-utils rpcbind system-config-
firewall-tui
 Modify the selinux file to disable SELINUX
$ sudo gedit /etc/sysconfig/selinux and set
SELINUX=disabled
$ setenforce 0
 Make a folder to be the mount point.
$ sudo mkdir /var/lib/libvirt/images
 Start the following services
$ sudo chkconfig nfs on
$ sudo chkconfig nfslock on
$ sudo chkconfig rpcbind on
 Restart the following services on Server machine once you completed all the above
steps:
$ sudo service rpcbind restart
$ sudo service nfs restart
$ sudo service nfslock restart
 To mount (do this as root):

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 Append the following line to fstab file:
$ sudo gedit /etc/fstab
<Shared directory> <mount point> <type> <auto> 0 0
172.16.30.48://var/lib/libvirt/images
/var/lib/libvirt/images nfs auto 0 0
172.16.30.48: Server name
172.16.30.48:/var/lib/libvirt/images: mount File
/var/lib/libvirt/images: Mounting point on client machine (172.16.30.46)
nfs : Type
 Mount shared nfs file on client machine:
$ sudo mount -t nfs
172.16.30.48://var/lib/libvirt/images
/var/lib/libvirt/images