Transcript xen-training - ntcap.nic.in

Virtualization
What is Virtualization

Virtualization is a technique of partitioning or dividing the
resources of a single server into multiple segregated execution
environments. Each of these environments runs independently of
the other, thus allowing multiple operating systems to run on the
same hardware. This concept has been widely used in the world
of mainframe computers over the years, and is now gaining a lot
of traction in the world of enterprise IT systems. Each execution
environment is called a guest and the server on which they
execute is called the host. The software running on the host that
acts as a bridge between the host and the guests, and that enables
these multiple execution environments is commonly referred to
as the Virtual Machine Monitor (VMM) or a Hypervisor.
Why Virtualize?
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Server Consolidation (hard and soft costs)
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Reduction of Complexity
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Isolation
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Platform Uniformity
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Legacy Support
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More effectively manage workloads
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Provide reliable testing infrastructure
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Faster deployment/provisioning (golden images)
The Virtualization Approach
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OS Instances for running specific apps
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Fail-over between OS instances
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greatly reduces recovery time
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Separate components to avoid failure
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Enhanced security with “separation”
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Auto-provisioning for recovery
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Performance penalties
Virtualization Overview
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Single OS image: Virtuozo
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Group user processes into resource containers
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Hard to get strong isolation
Full virtualization: VMware, VirtualPC, QEMU
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Run multiple unmodified guest OSes
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Hard to efficiently virtualize x86
Para-virtualization: UML, Xen
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Run multiple guest OSes ported to special arch
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Arch Xen/x86 is very close to normal x86
Virtual machines
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Basic Terminology
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Host OS: The OS running on a physical machine
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Guest OS: The OS running on a virtual machine
Today different approaches
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Full virtualization: Run an unmodified OS
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Paravirtualization: Modification of OS for
performance
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Emulation: Host OS and Guest OS can have
different architecture
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Hardware support: Intel-VT, AMD-V
XEN
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Xen is an open-source paravirtualization technology
that provides a platform for running multiple
operating systems in parallel on one physical
hardware resource, while providing close to native
performance. Xen supports several operating
systems—Linux
Xen vs VMWare Architecture
Guest 1
Parent
Guest 1
Guest 2
Guest 2
VMM
VMM
Host OS
Hardware
Xen Based Architecture
Hardware
VMWare Based Architecture
Full virtualization

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Full virtualization provides complete abstraction between the
hardware and the guest operating system. In this scenario, the guest
operating system is provided a complete virtual physical environment
in which to run and, as such, is unaware that it is running inside a
virtual machine. One advantage of full virtualization is that the
operating system does not need to be modified in order to run in a
virtualized environment. This means that proprietary operating
systems such as Windows can be run on Linux systems.
Disadvantages of full virtualization are that performance is slightly
reduced as compared to para-virtualization, and some virtualization
platforms, such as Xen, require CPUs with special virtualization
support built in (such as Intel-VT and AMD-V).
Para-Virtualization

Para-virtualization requires that a guest operating
system be modified to support virtualization. This
typically means that guest operating systems are
limited to open source systems such as Linux. It is
also not possible to migrate a running guest OS from
one server to another. The advantage to this
approach, however, is that a para-virtualized guest
system comes closer to native performance than a
fully virtualized guest, and the latest virtualization
CPU support is not needed.
Prerequirement
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Linux Based O.S.
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Hardware support: Intel-VT, AMD-V (for full virtu)
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RAM 512 MINIMUM (256 for host and 256 for
guest machine)
2 gb Space in Hard Disk.
Prerequirement (2)
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Need to create the yum repository. Follow below steps:
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Mkdir /repo
Mount /rhel5.iso /repo -o loop
OR
Mount /dev/cdrom /repo
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Vi /etc/yum.repos.s/local.repo
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name=rhel-base
baseurl=file:///repo/Server/
enabled=1
gpgcheck=0
[rhel-xen]
name=rhel - xen
baseurl=file:///repo/VT/
enabled=1
gpgcheck=0
Xen Installation
'
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To install Xen Virtualization run blow command:
yum groupinstall virtualization
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Need to boot machine with xen kernel.
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Verify xen kernel by below command:
uname -r
Creating a Paravirtualized Virtual
Machine
Xen Management Console
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To start Xen management console, run virt-manager
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Application tab --> System Tools --> Virtual Machine Manager
Xen Management Console (2)
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This Screen will
appear.
Xen Management Console (3)
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Click on file menu.
Select the open
connection.
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This screen will appear.
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Click on connect button.
Xen Management Console (4)
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This screen will appear.
Here select the localhost
and click on new.
Xen Management Console (5)
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Click on forward.
Xen Management Console (6)
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Select the type of
virtualization.
Xen Management Console (7)
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Type the name of virtual
machine.
Xen Management Console (8)
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Address of installation
source.
Xen Management Console (9)
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Assign hard drive for
virtual machine.
Xen Management Console (10)
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Select the type of
network.
Xen Management Console (11)
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Specify the memory for
virtual machine.
Xen Management Console (12)
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Wizard is completed,
now click on finish.
Create a paravirtualized vm from
cmd
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virt-install \
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--paravirt \
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--name demo \
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--ram 500 \
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--file /var/lib/xen/images/demo.img \
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--file-size 6 \
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--vnc \
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--location
http://download.fedora.redhat.com/pub/fedora/linu
Creating a Full Virtualized Virtual
Machine
Xen Management Console
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To start Xen management console, run virt-manager
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Application tab --> System Tools --> Virtual Machine Manager
Xen Management Console (2)
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This Screen will
appear.
Xen Management Console (3)

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Click on file menu.
Select the open
connection.
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This screen will appear.

Click on connect button.
Xen Management Console (4)


This screen will appear.
Here select the localhost
and click on new.
Xen Management Console (5)
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Click on forward.
Xen Management Console (6)
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Select the Fully
Virtualized Machine
Xen Management Console (7)
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Locate the iso file of
windows.
OR
Insert Windows CD.
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Select the OS Type.
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Select the OS Variant.
Xen Management Console (8)

Assign hard drive for
virtual machine.
Xen Management Console (9)

Select the type of
network.
Xen Management Console (10)

Specify the memory for
virtual machine.
Xen Management Console (11)

Wizard is completed,
now click on finish.
Create full virtualized vm from cm
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# virt-install \
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--hvm \
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--name demo \
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--ram 500 \
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--nodisk \
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--livecd \
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--vnc \
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--cdrom /root/fedora7live.iso
Xen Resource Management (1)
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Connect with localhost.
Xen Resource Management (2)
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Click on connect.
Xen Resource Management (3)
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This screen will appear.
Select the Guest OS and
click on details.
Xen Resource Management (4)
•
Here we can define
the number of cpus.
Xen Resource Management (5)
•
Here we can set the
size of memory.
Xen Resource Management (6)
•
Here we can add
more virtual harddisk.
Xen Resource Management (7)
•
Here we can add more
NIC.
XEN Live Migration
Migrating whole OS with running applications
(kernel-internal state and application-level)
rather than single processes
Xen Migration type
•
Red Hat Virtualization includes the capabilities to
support migration of para-virtualized guests
between Red Hat Virtualization servers. Migration
can either be performed in two ways:
•
Offline mode using the command xm migrate
VirtualMachineName HostName. In this mode
the virtual machine will be stopped on the original
host and restarted on the new host.
•
Live mode using the --live option for the command
xm migrate --live
VirtualMachineNameHostName.
Why Xen Migration
•
Load Balancing.
•
Move a staging server to live server.
•
Server mentenance.
•
Optimize performance of server.
Xen Migration Scenario
Vm1 migration
vm1
host1
host2
nfssrv
Vm1
image
LAN Connectivity
Xen Migration Requirement
•
Xen Migration should be active.
•
Configure the NFS for shared storage
•
Create paravirtualized virtual machine, which use
the NFS as storage.
Xen Migration Setup
•
To enable the use of migration a few changes must
be made to configuration file /etc/xen/xendconfig.sxp. By default migration is disabled.
•
Need to do changes on both xen host machines.
Xen Migration Setup(1)
•
Enabling migration.
–
Modify the following entries in /etc/xen/xendconfig.sxp to enable migration, remove the
comments preceding the parameters in the
configuration file:
–
(xend-relocation-server yes)
–
(xend-relocation-port 8002)
–
(xend-relocation-address '')
–
(xend-relocation-hosts-allow '')
Xen Migration Setup(2)
•
Restart Xend:
service xend restart
•
Verify the Xen relocation server has started and is
listening on the dedicated port for Xen migrations
(8002):
–
# lsof -i :8002
–
COMMAND PID USER
SIZE NODE NAME
FD TYPE DEVICE
Xen Migration Setup(3)
•
•
Setting up the NFS server.
–
# mkdir /xentest
–
# mount /dev/sdb /xentest
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# cat /etc/exports
–
/xentest *(rw,async,no_root_squash)
Restart the nfs service
–
Service nfs restart
Xen Migration Setup(4)
•
Verify it is exported via NFS:
–
# showmount -e et-virt07
–
Export list for et-virt07:
–
/xentest *
Xen Migration Setup(5)
•
After starting the NFS server, we can then mount it
on host1, host2:
–
mount nfssrv:/xen /xen
Xen Migration Setup(6)
•
Create a guest machine using nfs shared storage on
host1 only.
•
After complete the installation shutdown the guest
machine. Now perform the migration from host1 to
host2.
•
xm migrate rhel5 host2
Xen Migration Setup(7)
•
Proceed to start Xen guest on host1
•
Now perform the live migration
•
xm migrate –live rhel5-2 host2
Note: Guest machine should have it's disk over nfs
shared storage.
Xen Migration Setup(8)
•
Try to open multiple terminal windows on both
Xen hosts with the following command:
–
•
watch -n1 xm list
And ping the guest machine
Xen Management Commands
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To connect a remote machine from virt-manager
–
virt-manager -c xen+ssh://192.168.1.20/system
Xen Management Commands
•
To make a clone of exist Virtual machine
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# virt-clone \
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--original demo \
–
--name newdemo \
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--file /var/lib/xen/images/newdemo.img
Xen Management Commands
• To start a vartual machine
– Xm create machinename -c
Xen Management Commands
•
To see the list of virtual machines
–
# xm list
Name
ID Mem VCPUs State Time(s)
Domain-0
0 1302 1 r----- 5809.3
WinXP-LVM-HVM 4 256 1 -b---- 31.8
fedora.fc6.nfs 1 256 1 -b---- 11.2
Xen Management Commands
•
Attach to domain domain-id’s console.
–
Xm console 121
Xen Management Commands
•
Immediately terminate the domain domain-id.
–
Xm destroy 101
Xen Management Commands
•
Adding an ISO file as a CD-ROM to a guest
configuration file
–
['file:/var/lib/xen/images/win2003sp1.dsk,hda,w',\
–
'file:/xen/trees/ISO/WIN/en_windows_server_2003_with_sp1_stan
dard.iso,hdc:cdrom,r',]
Xen Management Commands
•
Mount an ISO as a Disk
–
xm block-attach guestdomain file://opt/rhel5-2.iso
/dev/hdc ro
Xen Management Commands
•
Adding a file based container as additional storage
to a guest.
–
dd if=/dev/zero of=FileName.img bs=1M seek=4096
count=0
OR
–
dd if=/dev/zero of=FileName.img bs=1M
count=4096
–
disk = [
'tap:aio:/var/lib/xen/images/rhel5vm01.dsk,xvda,w', ]
OR
Xen Management Commands
•
Use the following xm commands for monitoring
and troubleshooting:
–
xm top
–
xm dmesg
–
xm info
–
xm log
–
xm uptime
–
xm sysrq
–
xm dump-core
Xen Management Commands
• Starting domains automatically during system boot
– # cd /etc/xen
– # cd auto
– # ls
– # ln -s ../rhel5vm01 .
– # ls -l
– lrwxrwxrwx 1 root root 14 Dec 14 10:02 rhel5vm01 ->
../rhel5vm01
Xen Management Commands
•
To mount xen guest image
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1. check the partition on the image
–
# fdisk -lu
–
The result will be something like this:
–
2. Mount using offset option
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# mount -o loop,offset=106929152 /path/to/image
/mnt , where 106929152=208846*512, 208846 is
the start of the partition. Using this way, you only
mount the second partition and not the whole image
Xen Management tool
•
virt-p2v is an experimental live CD for migrating
physical machines to virtual machine guests.
•
Download P2V from RedHat Website.
–
•
http://et.redhat.com/~rjones/virt-p2v/download.html
See the documentation and screenshots on below
link
–
http://et.redhat.com/~rjones/virt-p2v/
Convirt
•
http://www.convirture.com/wiki/index.php?title=Installation#CentOS.2FRed_Hat
_Enterprise_Linux_5.x
–
cd /etc/yum.repos.d
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wget --no-cache
http://www.convirture.com/repos/definitions/rhel/5.x
/convirt.repo
–
yum install convirt
–
convirt