This guide explains how you can install and use KVM for creating and running virtual machines on a CentOS 6.2 server. I will show how to create image-based virtual machines and also virtual machines that use a logical volume (LVM). KVM is short for
Kernel-based Virtual Machine and makes use of hardware virtualization, i.e., you need a CPU that supports hardware virtualization, e.g. Intel VT or AMD-V.
I do not issue any guarantee that this will work for you!
1 Preliminary Note
I'm using a CentOS 6.2 server with the hostname
server1.example.com and the IP address
192.168.0.100 here as my KVM host.
I had SELinux disabled on my CentOS 6.2 system. I didn't test with SELinux on; it might work, but if not, you better switch off SELinux as well:
vi /etc/selinux/config
Set
SELINUX=disabled...
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of these two values:
# targeted - Targeted processes are protected,
# mls - Multi Level Security protection.
SELINUXTYPE=targeted
|
... and reboot:
reboot
We also need a desktop system where we install virt-manager so that we can connect to the graphical console of the virtual machines that we install. I'm using a Fedora 16 desktop here.
2 Installing KVM
CentOS 6.2 KVM Host:
First check if your CPU supports hardware virtualization - if this is the case, the command
egrep '(vmx|svm)' --color=always /proc/cpuinfo
should display something, e.g. like this:
[root@server1 ~]# egrep '(vmx|svm)' --color=always /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall
nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy misalignsse
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall
nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy misalignsse
[root@server1 ~]#
If nothing is displayed, then your processor doesn't support hardware virtualization, and you must stop here.
Now we import the GPG keys for software packages:
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY*
To install KVM and
virtinst (a tool to create virtual machines), we run
yum install kvm libvirt python-virtinst qemu-kvm
Then start the libvirt daemon:
/etc/init.d/libvirtd start
To check if KVM has successfully been installed, run
virsh -c qemu:///system list
It should display something like this:
[root@server1 ~]# virsh -c qemu:///system list
Id Name State
----------------------------------
[root@server1 ~]#
If it displays an error instead, then something went wrong.
Next we need to set up a network bridge on our server so that our virtual machines can be accessed from other hosts as if they were physical systems in the network.
To do this, we install the package
bridge-utils...
yum install bridge-utils
... and configure a bridge. Create the file
/etc/sysconfig/network-scripts/ifcfg-br0 (please use the
IPADDR,
PREFIX,
GATEWAY, DNS1 and
DNS2 values from the
/etc/sysconfig/network-scripts/ifcfg-eth0 file); make sure you use
TYPE=Bridge, not
TYPE=Ethernet:
vi /etc/sysconfig/network-scripts/ifcfg-br0
DEVICE="br0"
NM_CONTROLLED="yes"
ONBOOT=yes
TYPE=Bridge
BOOTPROTO=none
IPADDR=192.168.0.100
PREFIX=24
GATEWAY=192.168.0.1
DNS1=8.8.8.8
DNS2=8.8.4.4
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System br0" |
Modify
/etc/sysconfig/network-scripts/ifcfg-eth0 as follows (comment out
BOOTPROTO,
IPADDR,
PREFIX,
GATEWAY,
DNS1, and
DNS2 and add
BRIDGE=br0):
vi /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
NM_CONTROLLED="yes"
ONBOOT=yes
HWADDR=00:1E:90:F3:F0:02
TYPE=Ethernet
#BOOTPROTO=none
#IPADDR=192.168.0.100
#PREFIX=24
#GATEWAY=192.168.0.1
#DNS1=8.8.8.8
#DNS2=8.8.4.4
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0"
UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
BRIDGE=br0 |
Restart the network...
/etc/init.d/network restart
... and run
ifconfig
It should now show the network bridge (
br0):
[root@server1 ~]# ifconfig
br0 Link encap:Ethernet HWaddr 00:1E:90:F3:F0:02
inet addr:192.168.0.100 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::21e:90ff:fef3:f002/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:103 errors:0 dropped:0 overruns:0 frame:0
TX packets:79 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:7434 (7.2 KiB) TX bytes:21398 (20.8 KiB)
eth0 Link encap:Ethernet HWaddr 00:1E:90:F3:F0:02
inet6 addr: fe80::21e:90ff:fef3:f002/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:19511 errors:0 dropped:0 overruns:0 frame:0
TX packets:11592 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:25980124 (24.7 MiB) TX bytes:1104371 (1.0 MiB)
Interrupt:28 Base address:0x6000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:7 errors:0 dropped:0 overruns:0 frame:0
TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3608 (3.5 KiB) TX bytes:3608 (3.5 KiB)
virbr0 Link encap:Ethernet HWaddr 6A:12:69:18:2B:05
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
[root@server1 ~]#
3 Installing virt-viewer Or virt-manager On Your Fedora 16 Desktop
Fedora 16 Desktop:
We need a means of connecting to the graphical console of our guests - we can use virt-manager for this. I'm assuming that you're using a Fedora 16 desktop.
Become root...
su
... and run...
yum install virt-manager libvirt qemu-system-x86 openssh-askpass
... to install virt-manager.
(If you're using an Ubuntu 11.10 desktop, you can install virt-manager as follows:
sudo apt-get install virt-manager
)
4 Creating A Debian Squeeze Guest (Image-Based) From The Command Line
CentOs 6.2 KVM Host:Now let's go back to our CentOS 6.2 KVM host.
Take a look at
man virt-install
to learn how to use virt-install.
We will create our image-based virtual machines in the directory
/var/lib/libvirt/images/ which was created automatically when we installed KVM in chapter two.
To create a Debian Squeeze guest (in bridging mode) with the name
vm10, 512MB of RAM, two virtual CPUs, and the disk image
/var/lib/libvirt/images/vm10.img (with a size of 12GB), insert the Debian Squeeze Netinstall CD into the CD drive and run
virt-install --connect qemu:///system -n vm10 -r 512 --vcpus=2 --disk path=/var/lib/libvirt/images/vm10.img,size=12 -c /dev/cdrom --vnc --noautoconsole --os-type linux --os-variant debiansqueeze --accelerate --network=bridge:br0 --hvm
Of course, you can also create an ISO image of the Debian Squeeze Netinstall CD (please create it in the
/var/lib/libvirt/images/ directory because later on I will show how to create virtual machines through virt-manager from your Fedora desktop, and virt-manager will look for ISO images in the
/var/lib/libvirt/images/ directory)...
dd if=/dev/cdrom of=/var/lib/libvirt/images/debian-6.0.2.1-amd64-netinst.iso
... and use the ISO image in the virt-install command:
virt-install --connect qemu:///system -n vm10 -r 512 --vcpus=2 --disk path=/var/lib/libvirt/images/vm10.img,size=12 -c /var/lib/libvirt/images/debian-6.0.2.1-amd64-netinst.iso --vnc --noautoconsole --os-type linux --os-variant debiansqueeze --accelerate --network=bridge:br0 --hvm
The output is as follows:
[root@server1 ~]# virt-install --connect qemu:///system -n vm10 -r 512 --vcpus=2 --disk path=/var/lib/libvirt/images/vm10.img,size=12 -c /var/lib/libvirt/images/debian-6.0.2.1-amd64-netinst.iso --vnc --noautoconsole --os-type linux --os-variant debiansqueeze --accelerate --network=bridge:br0 --hvm
Starting install...
Allocating 'vm10.img' | 12 GB 00:00
Creating domain... | 0 B 00:00
Domain installation still in progress. You can reconnect to
the console to complete the installation process.
[root@server1 ~]#
5 Connecting To The Guest
Fedora 16 Desktop:
The KVM guest will now boot from the Debian Squeeze Netinstall CD and start the Debian installer - that's why we need to connect to the graphical console of the guest. You can do this with virt-manager on the Fedora 16 desktop.
Go to
Applications > System Tools > Virtual Machine Manager to start virt-manager:
When you start virt-manager for the first time, you will most likely see the following message (
Unable to open a connection to the libvirt management daemon.). You can ignore this because we don't want to connect to the local libvirt daemon, but to the one on our CentOS 6.2 KVM host. Click on
Close...
... and go to
File > Add Connection... to connect to our CentOS 6.2 KVM host:
Select
QEMU/KVM as
Hypervisor, then check
Connect to remote host, select
SSH in the
Method drop-down menu, type in root as the
Username and the hostname (
server1.example.com) or IP address (
192.168.0.100) of the CentOS 6.2 KVM host in the
Hostname field. Then click on
Connect:
If this is the first connection to the remote KVM server, you must type in
yes and click on
OK:
Afterwards type in the root password of the CentOS 6.2 KVM host:
You should see
vm10 as running. Mark that guest and click on the
Open button to open the graphical console of the guest:
Type in the root password of the KVM host again:
You should now be connected to the graphical console of the guest and see the Debian installer:
Now install Debian as you would normally do on a physical system. Please note that at the end of the installation, the Debian guest needs a reboot. The guest will then stop, so you need to start it again, either with virt-manager or like this on our CentOS 6.2 KVM host command line:
CentOS 6.2 KVM Host:
virsh --connect qemu:///system
start vm10
quit
Afterwards, you can connect to the guest again with virt-manager and configure the guest. If you install OpenSSH (package
openssh-server) in the guest, you can connect to it with an SSH client (such as
PuTTY).
6 Creating A Debian Squeeze Guest (Image-Based) From The Desktop With virt-manager
Instead of creating a virtual machine from the command line (as shown in chapter 4), you can as well create it from the Fedora desktop using virt-manager (of course, the virtual machine will be created on the CentOS 6.2 KVM host - in case you ask yourself if virt-manager is able to create virtual machines on remote systems).
To do this, click on the following button:
The
New VM dialogue comes up. Fill in a name for the VM (e.g.
vm11), select
Local install media (ISO image or CDROM), and click on
Forward:
Next select
Linux in the
OS type drop-down menu and
Debian Squeeze in the
Version drop-down menu, then check
Use ISO image and click on the
Browse... button:
Select the
debian-6.0.2.1-amd64-netinst.iso image that you created in chapter 4 and click on
Choose Volume:
Now click on
Forward:
Assign memory and the number of CPUs to the virtual machine and click on
Forward:
Now we come to the storage. Check
Enable storage for this virtual machine, select
Create a disk image on the computer's hard drive, specify the size of the hard drive (e.g. 12GB), and check
Allocate entire disk now. Then click on
Forward:
Now we come to the last step of the
New VM dialogue. Go to the
Advanced options section. Select
Host device vnet0 (Bridge 'br0'); that is the name of the bridge which we created in chapter 2. Click on
Finish afterwards:
The disk image for the VM is now being created:
Afterwards, the VM will start. Type in the root password of the CentOS 6.2 KVM host:
You should now be connected to the graphical console of the guest and see the Debian installer:
Now install Debian as you would normally do on a physical system.
7 Managing A KVM Guest From The Command Line
CentOS 6.2 KVM Host:
KVM guests can be managed through
virsh, the "virtual shell". To connect to the virtual shell, run
virsh --connect qemu:///system
This is how the virtual shell looks:
[root@server1 ~]# virsh --connect qemu:///system
Welcome to virsh, the virtualization interactive terminal.
Type: 'help' for help with commands
'quit' to quit
virsh #
You can now type in commands on the virtual shell to manage your guests. Run
help
to get a list of available commands:
virsh # help
Grouped commands:
Domain Management (help keyword 'domain'):
attach-device attach device from an XML file
attach-disk attach disk device
attach-interface attach network interface
autostart autostart a domain
blkiotune Get or set blkio parameters
blockpull Populate a disk from its backing image.
blockjob Manage active block operations.
console connect to the guest console
cpu-baseline compute baseline CPU
cpu-compare compare host CPU with a CPU described by an XML file
create create a domain from an XML file
define define (but don't start) a domain from an XML file
destroy destroy (stop) a domain
detach-device detach device from an XML file
detach-disk detach disk device
detach-interface detach network interface
domid convert a domain name or UUID to domain id
domjobabort abort active domain job
domjobinfo domain job information
domname convert a domain id or UUID to domain name
domuuid convert a domain name or id to domain UUID
domxml-from-native Convert native config to domain XML
domxml-to-native Convert domain XML to native config
dump dump the core of a domain to a file for analysis
dumpxml domain information in XML
edit edit XML configuration for a domain
inject-nmi Inject NMI to the guest
send-key Send keycodes to the guest
managedsave managed save of a domain state
managedsave-remove Remove managed save of a domain
maxvcpus connection vcpu maximum
memtune Get or set memory parameters
migrate migrate domain to another host
migrate-setmaxdowntime set maximum tolerable downtime
migrate-setspeed Set the maximum migration bandwidth
reboot reboot a domain
restore restore a domain from a saved state in a file
resume resume a domain
save save a domain state to a file
save-image-define redefine the XML for a domain's saved state file
save-image-dumpxml saved state domain information in XML
save-image-edit edit XML for a domain's saved state file
schedinfo show/set scheduler parameters
screenshot take a screenshot of a current domain console and store it into a file
setmaxmem change maximum memory limit
setmem change memory allocation
setvcpus change number of virtual CPUs
shutdown gracefully shutdown a domain
start start a (previously defined) inactive domain
suspend suspend a domain
ttyconsole tty console
undefine undefine an inactive domain
update-device update device from an XML file
vcpucount domain vcpu counts
vcpuinfo detailed domain vcpu information
vcpupin control or query domain vcpu affinity
version show version
vncdisplay vnc display
Domain Monitoring (help keyword 'monitor'):
domblkinfo domain block device size information
domblklist list all domain blocks
domblkstat get device block stats for a domain
domcontrol domain control interface state
domifstat get network interface stats for a domain
dominfo domain information
dommemstat get memory statistics for a domain
domstate domain state
list list domains
Host and Hypervisor (help keyword 'host'):
capabilities capabilities
connect (re)connect to hypervisor
freecell NUMA free memory
hostname print the hypervisor hostname
nodecpustats Prints cpu stats of the node.
nodeinfo node information
nodememstats Prints memory stats of the node.
qemu-attach QEMU Attach
qemu-monitor-command QEMU Monitor Command
sysinfo print the hypervisor sysinfo
uri print the hypervisor canonical URI
Interface (help keyword 'interface'):
iface-begin create a snapshot of current interfaces settings, which can be later commited (iface-commit) or restored (iface-rollback)
iface-commit commit changes made since iface-begin and free restore point
iface-define define (but don't start) a physical host interface from an XML file
iface-destroy destroy a physical host interface (disable it / "if-down")
iface-dumpxml interface information in XML
iface-edit edit XML configuration for a physical host interface
iface-list list physical host interfaces
iface-mac convert an interface name to interface MAC address
iface-name convert an interface MAC address to interface name
iface-rollback rollback to previous saved configuration created via iface-begin
iface-start start a physical host interface (enable it / "if-up")
iface-undefine undefine a physical host interface (remove it from configuration)
Network Filter (help keyword 'filter'):
nwfilter-define define or update a network filter from an XML file
nwfilter-dumpxml network filter information in XML
nwfilter-edit edit XML configuration for a network filter
nwfilter-list list network filters
nwfilter-undefine undefine a network filter
Networking (help keyword 'network'):
net-autostart autostart a network
net-create create a network from an XML file
net-define define (but don't start) a network from an XML file
net-destroy destroy (stop) a network
net-dumpxml network information in XML
net-edit edit XML configuration for a network
net-info network information
net-list list networks
net-name convert a network UUID to network name
net-start start a (previously defined) inactive network
net-undefine undefine an inactive network
net-uuid convert a network name to network UUID
Node Device (help keyword 'nodedev'):
nodedev-create create a device defined by an XML file on the node
nodedev-destroy destroy (stop) a device on the node
nodedev-dettach dettach node device from its device driver
nodedev-dumpxml node device details in XML
nodedev-list enumerate devices on this host
nodedev-reattach reattach node device to its device driver
nodedev-reset reset node device
Secret (help keyword 'secret'):
secret-define define or modify a secret from an XML file
secret-dumpxml secret attributes in XML
secret-get-value Output a secret value
secret-list list secrets
secret-set-value set a secret value
secret-undefine undefine a secret
Snapshot (help keyword 'snapshot'):
snapshot-create Create a snapshot from XML
snapshot-create-as Create a snapshot from a set of args
snapshot-current Get or set the current snapshot
snapshot-delete Delete a domain snapshot
snapshot-dumpxml Dump XML for a domain snapshot
snapshot-edit edit XML for a snapshot
snapshot-list List snapshots for a domain
snapshot-parent Get the name of the parent of a snapshot
snapshot-revert Revert a domain to a snapshot
Storage Pool (help keyword 'pool'):
find-storage-pool-sources-as find potential storage pool sources
find-storage-pool-sources discover potential storage pool sources
pool-autostart autostart a pool
pool-build build a pool
pool-create-as create a pool from a set of args
pool-create create a pool from an XML file
pool-define-as define a pool from a set of args
pool-define define (but don't start) a pool from an XML file
pool-delete delete a pool
pool-destroy destroy (stop) a pool
pool-dumpxml pool information in XML
pool-edit edit XML configuration for a storage pool
pool-info storage pool information
pool-list list pools
pool-name convert a pool UUID to pool name
pool-refresh refresh a pool
pool-start start a (previously defined) inactive pool
pool-undefine undefine an inactive pool
pool-uuid convert a pool name to pool UUID
Storage Volume (help keyword 'volume'):
vol-clone clone a volume.
vol-create-as create a volume from a set of args
vol-create create a vol from an XML file
vol-create-from create a vol, using another volume as input
vol-delete delete a vol
vol-download Download a volume to a file
vol-dumpxml vol information in XML
vol-info storage vol information
vol-key returns the volume key for a given volume name or path
vol-list list vols
vol-name returns the volume name for a given volume key or path
vol-path returns the volume path for a given volume name or key
vol-pool returns the storage pool for a given volume key or path
vol-upload upload a file into a volume
vol-wipe wipe a vol
Virsh itself (help keyword 'virsh'):
cd change the current directory
echo echo arguments
exit quit this interactive terminal
help print help
pwd print the current directory
quit quit this interactive terminal
virsh #
list
shows all running guests;
list --all
shows all guests, running and inactive:
virsh # list --all
Id Name State
----------------------------------
3 vm11 running
- vm10 shut off
virsh #
If you modify a guest's xml file (located in the
/etc/libvirt/qemu/ directory), you must redefine the guest:
define /etc/libvirt/qemu/vm10.xml
Please note that whenever you modify the guest's xml file in
/etc/libvirt/qemu/, you must run the
define command again!
To start a stopped guest, run:
start vm10
To stop a guest, run
shutdown vm10
To immediately stop it (i.e., pull the power plug), run
destroy vm10
Suspend a guest:
suspend vm10
Resume a guest:
resume vm10
These are the most important commands.
Type
quit
to leave the virtual shell.
8 Creating An LVM-Based Guest From The Command Line
CentOS 6.2 KVM Host:
LVM-based guests have some advantages over image-based guests. They are not as heavy on hard disk IO, and they are easier to back up (using
LVM snapshots).
To use LVM-based guests, you need a volume group that has some free space that is not allocated to any logical volume. In this example, I use the volume group
/dev/vg_server1 with a size of approx. 465GB...
vgdisplay
[root@server1 ~]# vgdisplay
--- Volume group ---
VG Name vg_server1
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size 465.27 GiB
PE Size 4.00 MiB
Total PE 119109
Alloc PE / Size 24480 / 95.62 GiB
Free PE / Size 94629 / 369.64 GiB
VG UUID jk2N5a-pQdV-I49Y-UCR9-A0Js-jEe0-0y6Ipg
[root@server1 ~]#
... that contains the logical volumes
/dev/vg_server1/lv_root with a size of approx. 50GB,
/dev/vg_server1/lv_home with a size of approx. 40GB, and
/dev/vg_server1/lv_swap (about 6GB) - the rest is not allocated and can be used for KVM guests:
lvdisplay
[root@server1 ~]# lvdisplay
--- Logical volume ---
LV Name /dev/vg_server1/lv_root
VG Name vg_server1
LV UUID il99XH-Q7QV-R16x-Q51X-GOzp-8uq1-aMUb82
LV Write Access read/write
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Name /dev/vg_server1/lv_home
VG Name vg_server1
LV UUID 2OqWO9-4P91-UDzK-K6i3-zgJz-vJWN-9OMXpi
LV Write Access read/write
LV Status available
# open 1
LV Size 40.00 GiB
Current LE 10240
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
--- Logical volume ---
LV Name /dev/vg_server1/lv_swap
VG Name vg_server1
LV UUID f5e90C-DMt8-896t-MmNo-S2FM-7hSd-gtVGjy
LV Write Access read/write
LV Status available
# open 1
LV Size 5.62 GiB
Current LE 1440
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
[root@server1 ~]#
I will now create the virtual machine
vm12 as an LVM-based guest. I want
vm12 to have 20GB of disk space, so I create the logical volume
/dev/vg_server1/vm12 with a size of 20GB:
lvcreate -L20G -n vm12 vg_server1
Afterwards, we use the virt-install command again to create the guest:
virt-install --connect qemu:///system -n vm12 -r 512 --vcpus=2 --disk path=/dev/vg_server1/vm12 -c /var/lib/libvirt/images/debian-6.0.2.1-amd64-netinst.iso --vnc --noautoconsole --os-type linux --os-variant debiansqueeze --accelerate --network=bridge:br0 --hvm
Please note that instead of
--disk path=/var/lib/libvirt/images/vm12.img,size=20 I use
--disk path=/dev/vg_server1/vm12, and I don't need to define the disk space anymore because the disk space is defined by the size of the logical volume
vm12 (20GB).
Now follow chapter 5 to install that guest.
9 Converting Image-Based Guests To LVM-Based Guests
CentOS 6.2 Host:
No let's assume we want to convert our image-based guest
vm10 into an LVM-based guest. This is how we do it:
First make sure the guest is stopped:
virsh --connect qemu:///system
shutdown vm10
quit
Then create a logical volume (e.g.
/dev/vg_server1/vm10) that has the same size as the image file - the image has 12GB, so the logical volume must have 12GB of size as well:
lvcreate -L12G -n vm10 vg_server1
Now we convert the image:
qemu-img convert /var/lib/libvirt/images/vm10.img -O raw /dev/vg_server1/vm10
Afterwards you can delete the disk image:
rm -f /var/lib/libvirt/images/vm10.img
Now we must open the guest's xml configuration file
/etc/libvirt/qemu/vm10.xml...
vi /etc/libvirt/qemu/vm10.xml
... and change the following section...
... so that it looks as follows:
Afterwards we must redefine the guest:
virsh --connect qemu:///system
define /etc/libvirt/qemu/vm10.xml
Still on the
virsh shell, we can start the guest...
start vm10
... and leave the
virsh shell:
quit
10 Links
