Virtualization allows for the abstraction and sharing of computer hardware resources like CPU, memory, storage and network capacity. The document introduces virtualization concepts and the tools KVM, Virsh and Virt-manager. It provides documentation on Virsh commands to manage domains (VMs), interfaces and networks. These include commands to define, start, suspend, resume VMs and interfaces, as well as take and restore VM snapshots to revert states. Managing VMs, interfaces and networks with Virsh commands allows administrators to efficiently share hardware resources across VMs.

1. Introduction to Virtualization, Virsh
Commands and Virt-Manager
Chin Pin Chang
04/07/2014
1

2. Outline
• Virtualization
– Introduction
– Types of Virtualization
– KVM
– Practice: KVM Installation
• Virsh Commands
– Introduction
– Practice: 3 Units
• Virt-Manager
• Conclusion
• References
2

3. Virtualization Introduction
• Virtualization is a broad term that refers to the
abstraction of computer physical resources such as
servers, network, memory and storage
3

4. Virtualization Introduction (cont.)
4
• Without Virtualization • With Virtualization

5. Why Virtualization
• Resource sharing
• High utilization of resource
• Reduce the number of physical servers
• Ability to bring up new server quickly
• Easy maintenance and monitoring
5

6. Types of Virtualization
• Server Virtualization
– Full virtualization, Paravirtualization, Hardware-assisted
virtualization
• Application Virtualization
• Desktop Virtualization
• Presentation Virtualization
• Network Virtualization
• Storage Virtualization
6

7. KVM Introduction
• KVM (Kernel-based Virtual Machine)
– A Linux kernel module that turns Linux into a hypervisor
– Full virtualization
7

8. Install KVM
• Check that your CPU supports hardware
virtualization
– 0 indicates that your CPU doesn’t support hardware
virtualization
– 1 or more indicates that it supports hardware
virtualization
8

9. Install KVM (cont.)
• Check BIOS
– Support
– Not support
9

10. Install KVM (cont.)
• Install necessary packages
– qemu-kvm
– libvirt-bin
– ubuntu-vm-builder
– bridge-utils
10

11. Add Users to Libvirtd and KVM Groups
• Add user "username" to libvirtd
• Add user " username" to KVM
• Need to re-login
11

12. Verify Installation
• Check groups
• Verify Installation
• Change the device's group
12

13. Install Virt-manager
• Install virt-manager
• Start virt-manager
13

14. Step 1 - Create new virtual machine
14

15. Step 2 – Locate install media
15

16. Step 3 – Specify CPU and Memory
16

17. Step 4 – Specify Storage
17

18. Step 5 – Specify Network
18

19. Install Ubuntu Server
19

20. Virsh Introduction
• Virsh is a command line interface tool for managing
VM and the hypervisor
20

21. Virsh Introduction (cont.)
• Virsh Commands Classification
21
– Domain management commands
– Domain monitoring commands
– Host and hypervisor commands
– Interface commands
– Network filter commands
– Virtual networking commands
– Node device commands
– Secrets commands
– Domain snapshot commands
– Storage pool commands
– Storage volume commands
– Virsh commands

22. Virsh Commands
Unit 1
Domain Management
22

23. Introduction
• Domain management
– Is used to manage VM
– Major commands: define, start, destroy, suspend,
resume and so on
23

24. How to use virsh
24

25. define
Item Content
Description Define, but don't start, a guest domain from an XML file
Input 1. XML file
Example # define vm1.xml
Response Domain vm1 defined from vm1.xml
25

26. Define a VM
26

27. XML for VM
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<name>vm1</name>
<uuid>b7cb10e2-c6af-a328-ad75-3e09747f0564</uuid>
<memory>524288</memory>
<currentMemory>524288</currentMemory>
<vcpu>1</vcpu>
<os>
<type arch='armv7l' machine='vexpress-a15'>hvm</type>
<kernel>/root/zImage</kernel>
<cmdline>earlyprintk=ttyAMA0 console=ttyAMA0 mem=512M root=/dev/vda rw
ip=192.168.20.56::192.168.20.101:vm1:eth0:off --no-log</cmdline>
<dtb>/root/guest-vexpress.dtb</dtb>
</os>
<features>
<acpi/>
<pae/>
</features>
<!-- <cpu>
<model>cortex-a15</model>
</cpu> -->
27

28. XML for VM (cont.)
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/usr/bin/qemu-system-arm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<source file='/root/nfs/ubuntu1G.img'/>
<target dev='vda' bus='virtio'/>
</disk>
<interface type='bridge'>
<source bridge='virbr0'/>
<mac address='52:54:00:12:34:55'/>
<model type='virtio'/>
</interface>
<console type='pty'/>
</devices>
</domain>
28

29. XML parameters
• name
– Virtual machine name
• uuid
– A globally unique identifier for the virtual machine
• current memory
– The actual allocation of memory for the VM
• type
– The type of operating system in the virtual machine
• kernel
– The fully-qualified path to the kernel image in the host OS
29

30. XML parameters (cont.)
• cmdline
– The arguments to be passed to the kernel at boot time
• dtb
– The fully-qualified path to the device tree binary image in
the host OS
• emulator
– The fully qualified path to the device model emulator
binary
• disk
– The main container for describing disks
• source file
– The resource on the host that is being accessed in the
guest
30

31. XML parameters (cont.)
• target
– The source can be accessed in the guest
• interface type
– A network interface visible to the guest
• source bridge
– The interface of the network
• mac address
– The address of the network
• model type
– The model of emulated network interface
31

32. start
Item Content
Description
Start a guest domain, either from the last managed save
state, or via a fresh boot if no managed save state is
present
Input 1.domain
Example # start vm1
Response Domain vm1 started
32

33. Start VM
33

34. domid
Item Content
Description Convert a domain name or UUID to domain id
Input 1. domain
Example # domid vm1
Response 1
34

35. domname
Item Content
Description
Convert a guest domain id or UUID to guest domain
name
Input 1. domain
Example # domname 1
Response vm1
35

36. domuuid
Item Content
Description
Convert a guest domain name or id to guest domain
UUID
Input 1. domain
Example # domuuid vm1
Response b7cb10e2-c6af-a328-ad75-3e09747f0564
36

37. VM Information
• The domain ID
• The domain name
• The domain uuid
37

38. autostart
Item Content
Description
Enable and disable the automatic starting of a guest
domain when the libvirt daemon starts
Input 1. domain
Example # autostart vm1
Response Domain vm1 marked as autostarted
38

39. Auto start VM
39

40. list
Item Content
Description Returns a list of guest domains
Input N/A
Example # list
Response
virsh # list
Id Name State
----------------------------------------------------
1 vm1 running
40

41. List VM
41

42. console
Item Content
Description Connect the virtual serial console for the guest
Input 1. domain
Example # console vm1
Response
Connected to domain vm1
Escape character is ^]
42

43. Connect to VM
43

44. Connect to VM (cont.)
44
• Launch Apache service
• Check Apache service

45. Connect to VM (cont.)
• Check the IP of the VM
45

46. Connect to VM (cont.)
• Check /var/www/index.html
• Web page
46

47. suspend
Item Content
Description Suspend a running guest domain
Input 1.domain
Example # suspend vm1
Response Domain vm1 suspended
47

48. Suspend VM
• Web page
48

49. resume
Item Content
Description Resume a guest domain
Input 1.domain
Example # resume vm1
Response Domain vm1 resumed
49

50. Resume VM
• Web page
50

51. save
Item Content
Description Save the running state of a guest domain to a file
Input
1.domain
2.file
Example # save vm1 image
Response Domain vm1 saved to image
51

52. restore
Item Content
Description Restore a guest domain
Input 1.file
Example # restore image
Response Domain restored from image
52

53. Save and Restore scenario
S0
Save
the VM
Restore
the VM
Start
the VM
Modify
index.htm
S0S2S1
53
Step 4Step 3Step 2Step 1

54. Step 1
• Save the VM
• The saved file
54

55. Step 2 and 3
• Start the VM
• Modify /var/www/index.html
• Web page
55

56. Step 4
• Restore the VM
• Web page
56

57. destroy
Item Content
Description
Immediately terminates a running guest domain,
releasing any resources in use by it
Input 1.domain
Example # destroy vm1
Response Domain vm1 destroyed
57

58. Destroy VM
58

59. The memory information of the host
• Before destroying the VM
• After destroying the VM
59

60. undefine
Item Content
Description Remove the configuration for an inactive guest domain
Input 1.domain
Example # undefine vm1
Response
Domain vm1 has been undefined
60

61. Undefine VM
61

62. Virsh Commands
Unit 2
Interface Management and
Network Management
62

63. Introduction
• Interface management
– To create an interface on the host for VM
63

64. iface-define
Item Content
Description Define a physical host network interface
Input 1. XML file
Example # iface-define br1.xml
Response Interface br1 defined from br1.xml
64

65. Define an interface
• Interface br1
65

66. XML for Interface
<interface type='bridge' name='br1'>
<start mode='onboot'/>
<bridge>
<interface type='vlan' name='bond0.1'>
<vlan tag='1'>
<interface name='bond1'/>
</vlan>
</interface>
</bridge>
</interface>
66

67. XML parameters
• interface type
– Network interface type
• interface name
– The name of interface
• bridge type
– The type of bridge
• vlan tag
– Use to tag of the vlan
67

68. iface-start
Item Content
Description Enables and starts a physical host network interface
Input 1. interface
Example # iface-start br1
Response Interface br1 started
68

69. Start interface
69

70. iface-name
Item Content
Description
Returns the physical host interface name for a MAC
address
Input 1. interface(MAC address)
Example # iface-name 3a:a0:42:19:ca:b2
Response br1
70

71. iface-mac
Item Content
Description
Returns the MAC address for a physical host network
interface
Input 1. interface
Example # iface-mac br1
Response 3a:a0:42:19:ca:b2
71

72. Interface Information
• The interface name
• The interface mac
72

73. iface-destroy
Item Content
Description
Shut down and disable a physical host network
interface
Input 1. interface
Example # iface-destroy br1
Response
Interface br1 destroyed
73

74. Destroy interface
74

75. iface-undefine
Item Content
Description
Removes the configuration information for a physical
host network interface
Input 1. interface
Example # iface-undefine br1
Response Interface br1 undefined
75

76. Undefine interface
76

77. Introduction
• Network management
– Libvirt has the capability to define virtual
networks which can then be used by domains
and linked to actual network devices
77

78. net-define
Item Content
Description
Adds a new permanent virtual network from an XML file,
without starting it
Input 1. file
Example # net-define vlan1.xml
Response Network vlan1 defined from vlan1.xml
78

79. Define network
• Network vlan1
79

80. XML for Network
<network >
<name>vlan1</name>
<forward mode='bridge'/>
<bridge name='br1' />
</network>
80

81. XML parameters
• name
– Virtual network name
• forward mode
– Inclusion of the forward element indicates that the virtual
network is to be connected to the physical LAN
• bridge name
– The name of a bridge device
81

82. net-start
Item Content
Description Starts a (previously defined) inactive virtual network
Input 1. network
Example # net-start vlan1
Response Network vlan1 started
82

83. Start network
83

84. net-autostart
Item Content
Description
Enable or disable the automatic starting of a virtual
network, when the libvirt daemon starts
Input 1. network
Example # net-autostart vlan1
Response Network vlan1 marked as autostarted
84

85. Auto start network
85

86. net-info
Item Content
Description Displays basic information for a virtual network
Input 1. network
Example # net-info vlan1
Response
Name vlan1
UUID f1f1cd7e-b623-4d7e-94c8-2047da1decef
Active: yes
Persistent: yes
Autostart: yes
Bridge: br1
86

87. Network Information
87

88. net-name
Item Content
Description
When given a network UUID, returns its corresponding
network name
Input 1. network
Example # net-name f1f1cd7e-b623-4d7e-94c8-2047da1decef
Response vlan1
88

89. net-uuid
Item Content
Description
When given a network name, returns its
corresponding UUID
Input 1. network
Example # net-uuid vlan1
Response f1f1cd7e-b623-4d7e-94c8-2047da1decef
89

90. Network Information
• The network name
• The network uuid
90

91. net-destroy
Item Content
Description Shuts down a running virtual network
Input 1. network
Example # net-destroy vlan1
Response
Network vlan1 destroyed
91

92. Destroy network
92

93. net-undefine
Item Content
Description
Removes an inactive virtual network from the libvirt
configuration
Input 1. network
Example # net-undefine vlan1
Response Network vlan1 has been undefined
93

94. Undefine network
94

95. Interface and Network scenario
95
Host
virbr0
br1 br2
VM1 VM2 VM3
IP: 192.168.1.101 192.168.1.102 192.168.1.103
vlan1
vlan2

96. Example
• Define the interfaces br1 and br2
96

97. XML for host
97
• br1.xml
<interface type='bridge' name='br1'>
<start mode='onboot'/>
<bridge>
<interface type='vlan' name='bond0.1'>
<vlan tag='1'>
<interface name='bond1'/>
</vlan>
</interface>
</bridge>
</interface>

98. XML for host (cont.)
98
• br2.xml
<interface type='bridge' name='br2'>
<start mode='onboot'/>
<bridge>
<interface type='vlan' name='bond0.2'>
<vlan tag=‘2'>
<interface name='bond2'/>
</vlan>
</interface>
</bridge>
</interface>

99. XML for VM
• Modify VM1.xml
• Modify VM2.xml
• Modify VM3.xml
99

100. Define VM
• Define VM1, VM2 and VM3
100

101. Start VM
• Start VM1, VM2 and VM3
101

102. Start interface
• Start interface br1 and br2
102

103. Connect to VM
• Assign IP (192.168.0.101) to VM1
103

104. Connect to VM (cont.)
• Assign IP (192.168.0.102) to VM2
104

105. Connect to VM (cont.)
• Assign IP (192.168.0.103) to VM3
105

106. Result
• VM1 ping VM2
• VM1 ping VM3
106

107. Result (cont.)
• VM3 ping VM1
• VM3 ping VM2
107

108. Virsh Commands
Unit 3
Snapshot and Migrate
108

109. Introduction
• Snapshot
– Snapshots take the disk, memory, and device state
of a VM at a point-of-time, and save it for future
use
• --disk-only
– The snapshot will only include disk state
109

110. Snapshot scenario
110
Create a
folder and
modify
index.htm
Start
the
VM
Restart
the
VM
Revert
the
snapshot
Step 4Step 3Step 2Step 1
S0 S3S2S1 S1
Step 5

111. snapshot-create
Item Content
Description Create a snapshot (disk and RAM) from XML
Input
1. domain
2. xml
Example # snapshot-create vm1 snaptest.xml
Response
Domain snapshot snaptest created from
'snaptest.xml'
111

112. 112
• Start VM
• Take a snapshot
Create a snapshot for VM

113. Create a folder in VM
113
• Start VM
• Create a folder "test"

114. Launch Apache service
• Check /var/www/index.html
• Web page
114

115. Launch Apache service (cont.)
• Modify the /var/www/index.html
• Web page
115

116. snapshot-revert
Item Content
Description Reverts a domain to a given snapshot
Input
1. domain
2. snapshotname
Example # snapshot-revert vm1 snaptest
Response N/A
116

117. Revert snapshot
• Folder
• Web page
117

118. snapshot-delete
Item Content
Description
Removes a snapshot, and all of it's children, from a
domain
Input
1. domain
2. snapshotname
Example # snapshot-delete --domain vm1 snaptest --metadata
Response Domain snapshot snaptest deleted
118

119. Delete snapshot
119

120. Introduction
• Migrate
– Migration is the process of moving a virtual
machine from one host or storage location to
another
120

121. Migration
121
Source
VM
Download
a file
Destination
VM
Download
a file
Migration
Network
IP: 192.92.26.120 IP: 192.92.26.108
NFS
/Data/image
VM
image

122. Set up NFS server for images
• Install NFS server packages
– nfs-common
– nfs-kernel-server
122
• Set shared path and permission

123. Set up NFS server for images (cont.)
• Start NFS server
123
• Check NFS path

124. Set up NFS client – hypervisor
• Install NFS client packages
– nfs-common
124
• Mount image
• Check

125. Set up NFS client – hypervisor (cont.)
• Restart NFS server
125
• Check image on client

126. migrate
Item Content
Description Migrates a guest domain to another host
Input
1.domain
2.dest uri
Example # migrate vm1 qemu+ssh://140.92.26.108/system
Response pass
126

127. Start VM
127

128. Download a file to VM
128

129. Migrate VM to destination host
• Source host
129
The URI of the destination host

130. After migration
• Destination host
130

131. Verify the file
• The file size
131

132. Virt-manager Introduction
• The virt-manager (Virtual Machine Manager)
application is a graphic user interface for managing
virtual machines through libvirt
132

133. Main window
133

134. Connection window
134

135. Define VM
135

136. Start VM
136

137. Connect to VM
137

138. Verify connection
138
• Virt-manager

139. Suspend VM
139

140. Resume VM
140

141. Save VM
141

142. Save VM (cont.)
142

143. Restore VM
143

144. Clone VM
144

145. Check CPU usage of VM
145

146. Destroy VM
146

147. Delete VM
147

148. Conclusion
• Virtualization
– High utilization of physical resource
• Virsh
– The main interface for managing virtualization
environment through Libvirt
• Virt-manager
– Graphic user interface for managing virtualization
environment through Libvirt
148

149. Question
149
• Mail:walkerchang@iii.org.tw

150. References
• http://libvirt.org/
• http://en.wikipedia.org/wiki/Virtualization
• http://en.wikipedia.org/wiki/Kernel-based_Virtual_Machine
• http://www.slideshare.net/trupti242/virtuallization-
questions#
• https://access.redhat.com/site/documentation/en-
US/Red_Hat_Enterprise_Linux/
• http://trac.nchc.org.tw/cloud
• https://help.ubuntu.com/community/KVM/Installation
• http://www.ubuntu-tw.org/modules/tinyd0/
150