Virtualisation in Red Hat Linux

AT Enterprise Virtualization solution

 

RHEV provides a complete solution for server virtualization management. Red Hat Enterprise Virtualization has been designed from the platform, Red Hat Enterprise Linux, which he extends the functionality, to bring down high barriers facing the ubiquity of virtualization in data centers. Red Hat Enterprise Linux has gained the trust of thousands of organizations and is installed on millions of systems in strategic workloads.

 

 

 

 

 

Installing the management console RHEVM

Before installing the management console on the server, verify that the following prerequisites is well respected:

 

- Operating system: Windows Server 2003 R2 or Windows Server 2008 (recommended)

- The IIS must be installed

- If you are running Windows Server 2003 you must install PowerShell 2.0 available on Windows Update or the Microsoft website.

- Microsoft Frameworks 3.5.1

 

 

Once the installation file to launch click Next and accept the terms of use.

 

 

Arrived at the above screen make sure all the boxes are checked and click Next.

 

 

 

 

Select "install a SQL Server 2005 Express Locally" and click next.

Check the installation directory and click next.

 

 

 

Uncheck the box strength SSL and click next

 

 

 

Fill in the requested information

 

Click next

 

 

 

 

Port Number: 25285

 

 

 

 

 

 

 

 

 

Click next

 

 

 

 

Click ignores the Manager installation begins.

 

 Administration RHEVM

 

 

This section shows the procedure to connect to the management console RHEVm

 

 

 

Open your browser enter the address bar:

 

http: // [ip address or name] / RHEVmanager

 

 

 

If this is not the case install the certificate by clicking the link.

 

 

 

 

The above screenshot is from the RHEVm authentication interface.

 

1 Installing RHEV hypervisor.

 

 

Boot from ISO hypervisor. After loading the next interface should appear:

 

 

 

 

Press 1 and input.

 

 

 

Select "configure" grave with the 1 key and confirm with input

Select the disk or hypervisor will install and validate.

Once the task by selecting validate the 3 ^rdinput (commit configuration).

 

Once the formatting you complete the wizard redisplay the main menu.

Press 2 (configure authentication)

 

 

 

 

Select the 1 ^st entered and enter the root password of the hypervisor.

Do the same for the 2 ^nd entrance.

Once set select the 3 ^rd entry to return to the main menu.

 

Configure the hostname by pressing 3 and then input.

When you ask the interface type the full name of the hypervisor

 

After configuring the hostname type 4 to configure the network.

 

Select the network interface configured (usually ETH0)

 

 

 

Type n and then enter

 

 

 

 

Type n and then enter.

 

 

 

Type S and enter

 

 

Configure the IP configuration of the hypervisor by following the instructions on the screen.

 

Then configure your DNS server in the same way by selecting DNS on the main menu of your hypervisor network configuration.

Do the same for the NTP server.

 

Select  Save And Return To Menu to return to the main menu.

 

 

Then save your RHN machine by pressing 5.

Select 1) Register to public RH n

Perform recording with your Red Hat Account

 

Once registration is complete RHN press 6 (Configure the host for red hat enterprise).

 

 

 

 

 

 

 

 

Type [ip of your server RHEVm]: 80

 

Then press enter

 

If communication is established correctly between the 2 machines hypervisor should return the following message:

 

 

"The RHEV Manager's address is set"

"The RHEV Manager's harbor is set. Do you even lift

 

 

Type [ip RHEVm your server]: 25285

Then press enter.

 

Once configuration is complete you will be back to the main menu.

 

Select 8 (install locally and reboot).

Once the installation is complete return on our management console.

 

 

If the configuration has been completed, a new HOST should be waiting in your RHEVM interface.

To enable it, right click on it and click approve. The host will be added to the cluster.

If no host is waiting, go to the hypervisor concerned and restarted the VDSM-reg service through the command-reg VDSM Service restart.

 

 

2 Configuring the Cluster

 

Configuring the storage space

 

 

 

Once your hypervisors added to your cluster, you must create a DATASTORE for your hosted VMs.

RHEV is able to manage multipathing fiber channel.

To do this go to the Storage tab and click the New button domain:

 

 

 

 

Domain Function: DATA

Storage Type: FCP

The list of VMFS will appear. (Do not forget to make the process of creating and VMFS presentation on the interface of the bay).Check VMFS converné and click the ADD button.

Then return to the tab and select DATASTORE on down the STORAGE tab and click the button attach storage.

 

 

 

 

Then select the VMFS that you have previously set.

This procedure is used to assign to a DataCenter storage esspace.

 

 

Repeat the process by creating a storage space with the following parameters:

 

- Domain function: ISO

- Storage Type: NFS

and attach it to your Data Center. This storage space will store ISO and templates.

The disadvantage is that the storage protocol must be absolutely NFS.

 

 

 

6 Managing ISOs

As we have seen above the ISOs library must have its own dedicated solely DATASTORE using the NFS protocol.

To upload ISOs secure ways REDHAT provides a tool installed with the Manager appointed ISO UPLOADER

 

ISO UPLOADER automatically detects your DATACENTER parameter is to autonomously for login with your NFS server.

To add an ISO image, click on ADD and select the ISO images you want UPLOADER. Once you have completed your list, click UPLOAD.ISO UPLOADER take charge of incorpérer ISOs directly to your library. We will see below how to exploit it.

 

On the command line you can also upload a ISO:

 

rhevm-iso-uploader -iso-domain = ISODomain upload <iso file>

 

7 Managing VMs

 

 

The management of virtual machines is indentique over other virtualisations products.

 

Create a new VM:

 

 

Click the Virtual Machines tab and click New Server:

 

 

 

Here you can set the configuration here "hardware" of your VM.

 

 

In this section, you can set the high availabilty system by checking 'Highly Available "

The choices "low", "Medium", "High" to define

 

 

 

 

In this section, pourez setting boot sequence and assign to your VM ISO you will eventually uploaded through the tool ISO UPLOADER.

 

 

After you do this job, click OK.

Once the task of creating the finished vm, it will cause him a disc and a virtual network interface. To do this click on your newly created VM and click "guide me".

 

 

Then click on "configure Network Interfaces".Once the parameters indicated as below click OK.

Red Hat Linux xen RHEL

Binary Xen rpm repositories for EL6

Take a look at these repositories:

Michael Young's EL6 Xen rpm repository (also includes xen dom0 capable kernel based on rhel6 2.6.32 kernel):http://xenbits.xen.org/people/mayoung/EL6.xen/http://xenbits.xen.org/people/mayoung/testing/Gitco.de repository is based on this tutorial, but contains xen dom0 capable kernel rpm based on the xen/kernel.org kernel (not rhel6 kernel):http://www.gitco.de/linux/x86_64/centos/6/http://www.gitco.de/linux/x86_64/centos/6/gitco-centos6-x86_64.repo

Additional repositories:

Fedora xendom0 kernel rpms by Michael Young:http://repos.fedorapeople.org/repos/myoung/dom0-kernel/http://wiki.alteeve.com/files/an-cluster/rhel6/

Red Hat Enterprise Linux 6 Xen 4.0 tutorial

This tutorial explains how to install and configure RHEL6 to run as Xen dom0 (host), running Xen hypervisor 4.0. Note that this is unsupported by Red Hat! See the end of this wiki page for more information about RHEL6 Xen binary rpm yum repository. This tutorial explains how to compile Xen and dom0 kernel from sources/srpms.

As a default RHEL6 does NOT:

RHEL6 does not ship Xen hypervisor or tools.RHEL6 does not ship Xen dom0 capable kernel.

As a default RHEL6 DOES:

RHEL6 runs as Xen PV (paravirtual) domU using the pvops framework in the default kernel.RHEL6 runs as Xen HVM (fully virtualized) guest.RHEL6 ships with optimized Xen PV-on-HVM drivers for RHEL6 Xen HVM guests.

Topics in this tutorial:

How to install and configure RHEL6 system for running as Xen dom0 (host).How to get Xen src.rpm from Fedora and rebuild and install it on RHEL6.How to install upstream Xen dom0 capable kernel on RHEL6.How to update the dom0 kernel to a newer version from the upstream git tree.How to use libvirt and virt-manager to manage Xen on RHEL6.Binary rpm repositories for EL6.More information and links.

TODO list for this tutorial:

Fix the src.rpm compilation examples, shouldn't build as root.Make sure everything works with SElinux enabled, and leave it enabled.

RHEL6 installation and configuration

Installation:

Download "rhel-server-6.0-x86_64-dvd.iso" from Red Hat Network (RHN).Burn it to DVDR, or if you have a server with remote management, use virtual media ISO mapping.Boot from the DVD.Install as usual.Choose "Basic Server" install.Disk Partitioning: Create /boot partition as primary, make it ext3 and at least 2 GB in size. Create LVM PV (Physical Volume) and VG (Volume Group) to fill the rest of the disk space. Create root as LVM volume, make it ext4, and at least 36 GB in size. Create swap as LVM volume, make it at least as big as the amount of RAM in your server.IMPORTANT! Make sure you leave FREE space in the LVM volume group. You can use that free space later to create LVM volumes for Xen VM virtual disks.In this tutorial the hostname is set to "el6.localdomain".

Screenshot of disk partitioning: 

Configuration after installation:

First fix networking by editing "/etc/sysconfig/network-scripts/ifcfg-ethX", usually "ifcfg-eth0", and make it look like:

[root@el6 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE="eth0" HWADDR="00:11:22:33:44:55" NM_CONTROLLED="no" ONBOOT="yes" BOOTPROTO="dhcp"

ie. make sure NM_CONTROLLED="no" and ONBOOT="yes". Then run "ifup eth0" to activate networking.

Make sure network service is set to start automatically:

[root@el6 ~]# chkconfig --list network

Make sure your Internet connection works OK at this point! Next make sure "/etc/hosts" file has an entry for your hostname:

[root@el6 ~]# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 127.0.0.1 el6 el6.localdomain

Full FQDN hostname in this example is "el6.localdomain".

Disable SElinux by editing "/etc/selinux/config" and make it have:

SELINUX=disabled

Then it's time to register your system to RHN, so you can fetch updates and install additional packages using yum.

Run "rhn_register" and fill in your RHN username and password. When registration is OK, there's an important extra step do!

You need to login to RHN website and:

Click "Manage Entitlements & Subscriptions".Click the correct (newly added) system.Click "(Alter Channel Subscriptions)".Select ""RHEL Server Optional (v. 6 64-bit x86_64)" channel.Click "Change Subscriptions".

Some required packages are only available in the "RHEL Server Optional (v. 6 64-bit x86_64)" channel. Failing to add that channel means you won't be able to install some required packages later on.

When you're done with RHN update the system and install latest (security) fixes:

[root@el6 ~]# yum update

Then install some commonly used tools:

[root@el6 ~]# yum install screen vim wget tcpdump ntp ntpdate man smartmontools links lynx ethtool xorg-x11-xauth

Then increase grub timeout from grub.conf, and comment out "hiddenmenu" option:

[root@el6 ~]# cat /boot/grub/grub.conf # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg00-lvroot # initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=10 splashimage=(hd0,0)/grub/splash.xpm.gz #hiddenmenu title Red Hat Enterprise Linux Server (2.6.32-71.7.1.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-71.7.1.el6.x86_64 ro root=/dev/mapper/vg00-lvroot rd_LVM_LV=vg00/lvroot rd_LVM_LV=vg00/lvswap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=fi crashkernel=auto rhgb quiet initrd /initramfs-2.6.32-71.7.1.el6.x86_64.img title Red Hat Enterprise Linux (2.6.32-71.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-71.el6.x86_64 ro root=/dev/mapper/vg00-lvroot rd_LVM_LV=vg00/lvroot rd_LVM_LV=vg00/lvswap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=fi crashkernel=auto rhgb quiet initrd /initramfs-2.6.32-71.el6.x86_64.img

At this point you should reboot the system to the newest kernel.

Installing required packages to compile Xen rpms

Install packages that are required to rebuild Xen src.rpm (all on one line):

[root@el6 ~]# yum groupinstall "Development tools" "Additional Development" "Debugging Tools" "System administration tools" "Compatibility libraries" "Console internet tools" "Desktop Platform Development"

This is around 212 MB of downloads.

Then install some additional packages that are required to build Xen with all features enabled:

[root@el6 ~]# yum install transfig wget texi2html libaio-devel dev86 glibc-devel e2fsprogs-devel gitk mkinitrd iasl xz-devel bzip2-devel pciutils-libs pciutils-devel SDL-devel libX11-devel gtk2-devel bridge-utils PyXML qemu-common qemu-img mercurial texinfo libuuid-devel

This is around 82 MB of downloads.

And finally 32bit version of glibc-devel is required aswell:

[root@el6 ~]# yum install glibc-devel.i686

Now you have all the basic tools, libraries and headers installed.

Rebuilding and installing Xen src.rpm

Fedora xen-4.0.1-6 rpm package includes some additional patches and fixes backported from upstream Xen 4.0.2-rc*.

[root@el6 ~]# mkdir /root/src && cd /root/src [root@el6 src]# wget http://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/releases/14/Everything/source/SRPMS/xen-4.0.1-6.fc14.src.rpm [root@el6 src]# rpm -i xen-4.0.1-6.fc14.src.rpm [root@el6 src]# cd /root/rpmbuild/SPECS [root@el6 SPECS]# rpmbuild -bb xen.spec

After a while you should see output like:

Wrote: /root/rpmbuild/RPMS/x86_64/xen-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-libs-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-runtime-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-hypervisor-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-doc-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-devel-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-licenses-4.0.1-6.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/xen-debuginfo-4.0.1-6.el6.x86_64.rpm

Try installing the rpms:

[root@el6 SPECS]# cd /root/rpmbuild/RPMS/x86_64/ [root@el6 x86_64]# rpm -Uvh xen*4.0.1-6*.rpm error: Failed dependencies: /usr/bin/qemu-nbd is needed by xen-runtime-4.0.1-6.el6.x86_64

So what's happening here? It seems RHEL6 does not have "qemu-common" rpm available, which includes "qemu-nbd" binary. So we need to grab qemu src.rpm from Fedora and rebuild it for RHEL6 to get the required "qemu-common" rpm.

Verify the version of "qemu" in RHEL6:

[root@el6 x86_64]# rpm -qa | grep qemu qemu-img-0.12.1.2-2.113.el6.x86_64

Ok, so it's version 0.12.x. Fedora 13 has qemu 0.12.5, so it's close enough:

[root@el6 x86_64]# cd /root/src [root@el6 src]# wget http://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/13/SRPMS/qemu-0.12.5-1.fc13.src.rpm [root@el6 src]# rpm -i qemu-0.12.5-1.fc13.src.rpm [root@el6 src]# cd /root/rpmbuild/SPECS [root@el6 SPECS]# rpmbuild -bb qemu.spec

After a while you'll see:

Wrote: /root/rpmbuild/RPMS/x86_64/qemu-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-kvm-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-img-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-common-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-user-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-x86-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-ppc-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-sparc-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-arm-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-mips-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-cris-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-m68k-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-system-sh4-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-kvm-tools-0.12.5-1.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/qemu-debuginfo-0.12.5-1.el6.x86_64.rpm

So now we have the required "qemu-common" rpm. Let's install it to satisfy the package dependencies:

[root@el6 SPECS]# cd /root/rpmbuild/RPMS/x86_64 [root@el6 x86_64]# rpm -Uvh qemu-common-0.12.5-1.el6.x86_64.rpm Preparing... ########################################### [100%] 1:qemu-common ########################################### [100%]

Now we can also install Xen rpms:

[root@el6 x86_64]# rpm -Uvh xen*4.0.1-6*.rpm Preparing... ########################################### [100%] 1:xen-licenses ########################################### [ 13%] 2:xen-libs ########################################### [ 25%] 3:xen-hypervisor ########################################### [ 38%] 4:xen-runtime ########################################### [ 50%] 5:xen ########################################### [ 63%] 6:xen-devel ########################################### [ 75%] 7:xen-doc ########################################### [ 88%] 8:xen-debuginfo ########################################### [100%]

Now you're done installing Xen hypervisor, tools and libraries.

Installing upstream Xen dom0 capable kernel

Note that we're installing upstream *Xen* kernel here, which is based on the long-term maintained kernel.org Linux 2.6.32.x kernel. This kernel is different from the RHEL6 kernel. Many drivers are newer versions in Red Hat's kernel, and Red Hat's kernel might have more features than the kernel.org kernel. Due to the driver version differences you might experience problems on some hardware, for example on servers using LSI/DELL RAID adapters. You might need to manually update driver versions to fix these problems on affected systems. See the end of this wiki page for more information about kernel versions.

Clone the kernel git repository from kernel.org and check out the "xen/stable-2.6.32.x" long-term maintained branch.

[root@el6 x86_64]# mkdir /root/kernel && cd /root/kernel [root@el6 kernel]# git clone git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git linux-2.6-xen [root@el6 kernel]# cd linux-2.6-xen [root@el6 linux-2.6-xen]# git checkout -b xen/stable-2.6.32.x origin/xen/stable-2.6.32.x

Now you have the kernel ready to be configured and compiled. Reference config-file used is for version "2.6.32.25". It should work with newer version aswell, "make oldconfig" takes care of that.

NOTE! The reference .config file has various debugging options enabled, so don't use this kernel config for performance benchmarks!

[root@el6 linux-2.6-xen]# wget -O .config http://pasik.reaktio.net/xen/kernel-config/config-2.6.32.25-pvops-dom0-xen-stable-x86_64 [root@el6 linux-2.6-xen]# make oldconfig [root@el6 linux-2.6-xen]# make -j4 bzImage && make -j4 modules && make modules_install

Then let's install the kernel and generate initrd (initramfs) image for the new kernel. Kernel version in this example is "2.6.32.25":

[root@el6 linux-2.6-xen]# depmod -a 2.6.32.25 [root@el6 linux-2.6-xen]# cp -a arch/x86/boot/bzImage /boot/vmlinuz-2.6.32.25 [root@el6 linux-2.6-xen]# cp -a System.map /boot/System.map-2.6.32.25 [root@el6 linux-2.6-xen]# cp -a .config /boot/config-2.6.32.25 [root@el6 linux-2.6-xen]# cd /boot [root@el6 boot]# dracut initramfs-2.6.32.25.img 2.6.32.25

NOTE! If you're using a system with LSI and/or Dell RAID adapters (using megaraid_sas driver) you need to manually update the driver version at this point! Linux 2.6.32.25 ships with too old driver version, and it wont' work (disks won't get enabled on system startup). See this email for information about updating the driver version:http://lists.xensource.com/archives/html/xen-devel/2010-11/msg00250.html .

Then it's time to modify "grub.conf" and add an entry for the Xen+dom0 combination:

[root@el6 ~]# cat /boot/grub/grub.conf # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg00-lvroot # initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=10 splashimage=(hd0,0)/grub/splash.xpm.gz #hiddenmenu title Red Hat Enterprise Linux Server (2.6.32-71.7.1.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-71.7.1.el6.x86_64 ro root=/dev/mapper/vg00-lvroot rd_LVM_LV=vg00/lvroot rd_LVM_LV=vg00/lvswap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=fi crashkernel=auto rhgb quiet initrd /initramfs-2.6.32-71.7.1.el6.x86_64.img title Red Hat Enterprise Linux (2.6.32-71.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-71.el6.x86_64 ro root=/dev/mapper/vg00-lvroot rd_LVM_LV=vg00/lvroot rd_LVM_LV=vg00/lvswap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=fi crashkernel=auto rhgb quiet initrd /initramfs-2.6.32-71.el6.x86_64.img title Xen 4.0 with Linux 2.6.32.25 dom0 root (hd0,0) kernel /xen.gz dom0_mem=1024M loglvl=all guest_loglvl=all module /vmlinuz-2.6.32.25 ro root=/dev/mapper/vg00-lvroot rd_LVM_LV=vg00/lvroot nomodeset module /initramfs-2.6.32.25.img

Then let's disable KSM services, those don't work with Xen currently:

[root@el6 ~]# chkconfig ksm off [root@el6 ~]# chkconfig ksmtuned off

And then it's time to reboot into Xen ! Remember to choose the Xen entry from grub:

[root@el6 ~]# reboot

Verifying Xen after reboot

[root@el6 ~]# xm list Name ID Mem VCPUs State Time(s) Domain-0 0 1024 4 r----- 93.9 [root@el6 ~]# xm info host  : el6.localdomain release  : 2.6.32.25 version  : #1 SMP Sun Nov 14 21:50:39 EET 2010 machine  : x86_64 nr_cpus  : 4 nr_nodes  : 1 cores_per_socket  : 4 threads_per_core  : 1 cpu_mhz  : 2826 hw_caps  : bfebfbff:20100800:00000000:00000940:0008e3fd:00000000:00000001:00000000 virt_caps  : hvm total_memory  : 8190 free_memory  : 7070 node_to_cpu  : node0:0-3 node_to_memory  : node0:7070 node_to_dma32_mem  : node0:3259 max_node_id  : 0 xen_major  : 4 xen_minor  : 0 xen_extra  : .1 xen_caps  : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 xen_scheduler  : credit xen_pagesize  : 4096 platform_params  : virt_start=0xffff800000000000 xen_changeset  : unavailable xen_commandline  : dom0_mem=1024M loglvl=all guest_loglvl=all cc_compiler  : gcc version 4.4.4 20100726 (Red Hat 4.4.4-13) (GCC) cc_compile_by  : root cc_compile_domain  : cc_compile_date  : Sun Nov 14 21:41:09 EET 2010 xend_config_format  : 4 [root@el6 ~]# uname -a Linux el6.localdomain 2.6.32.25 #1 SMP Sun Nov 14 21:50:39 EET 2010 x86_64 x86_64 x86_64 GNU/Linux

From the output above we can see we're running Xen hypervisor version 4.0.1 (xen_major, xen_minor, xen_extra) with Linux 2.6.32.25 dom0 kernel.

Updating the dom0 kernel

Linux 2.6.32.x is the long-term supported and maintained kernel from both kernel.org and xen.org, so it gets pretty frequent updates. Here are the steps to update your kernel tree so you don't have to clone the whole tree again.

Clean up and update the git tree, then check the changelog for the recent changes:

[root@el6 ~]# mkdir /root/kernel/linux-2.6-xen [root@el6 linux-2.6-xen]# make clean [root@el6 linux-2.6-xen]# git pull [root@el6 linux-2.6-xen]# git log | less

And then follow the steps in the previous chapters to build and install the new kernel version.

Online changelog for the "xen/stable-2.6.32.x" branch of the kernel git tree is located here: http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=shortlog;h=xen/stable-2.6.32.x .

Using libvirt and virt-manager with Xen

Install libvirt and virt-manager:

[root@el6 ~]# yum install libvirt virt-manager xorg-x11-xauth

The default version of libvirt in RHEL6 is not compiled with Xen support. You can verify this by using ssh with X11 forwarding from your laptop/desktop to your dom0, and trying to run "virt-manager":

[root@el6 ~]# virt-manager & [1] 2867 Unable to open connection to hypervisor URI 'xen:///': no connection driver available for xen:/// Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/connection.py", line 992, in _try_open None], flags) File "/usr/lib64/python2.6/site-packages/libvirt.py", line 111, in openAuth if ret is None:raise libvirtError('virConnectOpenAuth() failed') libvirtError: no connection driver available for xen:///

This can be fixed by rebuilding libvirt rpms with Xen support enabled.

NOTE! Before rebuilding libvirt src.rpm you need to boot into non-Xen environment! This is because some of the automated RHEL6 libvirt Xen-specific tests seem to fail in Xen dom0 environment, but work OK in baremetal.

Verify libvirt version in RHEL6:

[root@el6 ~]# rpm -qa | grep libvirt

RHEL 6.0 seems to have libvirt version 0.8.1.

Let's download the src.rpm from Red Hat ftp server, patch the spec file to enable Xen support, and try rebuilding it.

[root@el6 ~]# cd /root/src [root@el6 src]# wget ftp://ftp.redhat.com/pub/redhat/linux/enterprise/6Server/en/os/SRPMS/libvirt-0.8.1-27.el6.src.rpm [root@el6 src]# rpm -i libvirt-0.8.1-27.el6.src.rpm [root@el6 src]# wget http://pasik.reaktio.net/xen/patches/libvirt-spec-rhel6-enable-xen.patch [root@el6 src]# cd /root/rpmbuild/SPECS [root@el6 SPECS]# cp -a libvirt.spec libvirt.spec.orig [root@el6 SPECS]# patch -p0 < ~/src/libvirt-spec-rhel6-enable-xen.patch patching file libvirt.spec [root@el6 SPECS]# rpmbuild -bb libvirt.spec error: Failed build dependencies: libnl-devel >= 1.1 is needed by libvirt-0.8.1-27.el6.x86_64 xhtml1-dtds is needed by libvirt-0.8.1-27.el6.x86_64 libudev-devel >= 145 is needed by libvirt-0.8.1-27.el6.x86_64 libpciaccess-devel >= 0.10.9 is needed by libvirt-0.8.1-27.el6.x86_64 yajl-devel is needed by libvirt-0.8.1-27.el6.x86_64 libpcap-devel is needed by libvirt-0.8.1-27.el6.x86_64 avahi-devel is needed by libvirt-0.8.1-27.el6.x86_64 parted-devel is needed by libvirt-0.8.1-27.el6.x86_64 device-mapper-devel is needed by libvirt-0.8.1-27.el6.x86_64 numactl-devel is needed by libvirt-0.8.1-27.el6.x86_64 netcf-devel >= 0.1.4 is needed by libvirt-0.8.1-27.el6.x86_64

Ok, so we need more packages installed:

[root@el6 SPECS]# yum install libnl-devel xhtml1-dtds libudev-devel libpciaccess-devel yajl-devel libpcap-devel avahi-devel parted-devel device-mapper-devel numactl-devel netcf-devel

After that let's try again:

[root@el6 SPECS]# rpmbuild -bb libvirt.spec

After a while you'll see:

Wrote: /root/rpmbuild/RPMS/x86_64/libvirt-0.8.1-27.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/libvirt-client-0.8.1-27.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/libvirt-devel-0.8.1-27.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/libvirt-python-0.8.1-27.el6.x86_64.rpm Wrote: /root/rpmbuild/RPMS/x86_64/libvirt-debuginfo-0.8.1-27.el6.x86_64.rpm

Then let's install the xen-enabled rpms (note you need to use --force because the same version of libvirt is already installed):

[root@el6 ~]# cd /root/rpmbuild/RPMS/x86_64/ [root@el6 x86_64]# rpm -Uvh --force libvirt-0.8.1-27.el6.x86_64.rpm libvirt-client-0.8.1-27.el6.x86_64.rpm libvirt-python-0.8.1-27.el6.x86_64.rpm Preparing... ########################################### [100%] 1:libvirt-client ########################################### [ 33%] 2:libvirt ########################################### [ 67%] 3:libvirt-python ########################################### [100%]

Now make sure "libvirtd" is set to automatically start on boot:

[root@el6 ~]# chkconfig --list libvirtd libvirtd 0:off 1:off 2:off 3:on 4:on 5:on 6:off

Then it's time to reboot back to Xen !

Verifying libvirt with Xen

[root@el6 ~]# virsh list Id Name State ---------------------------------- 0 Domain-0 running [root@el6 ~]# xm list Name ID Mem VCPUs State Time(s) Domain-0 0 1024 4 r----- 52.8

So it seems to work. Now you're also able to use graphical "virt-manager" to manage Xen on RHEL6.

Bridge problems and errors with custom dom0 kernel

# brctl show bridge name    bridge id              STP enabled    interfaces virbr0         /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory /sys/class/net/virbr0/bridge: No such file or directory 8000.000000000000      yes

This problem happens because Red Hat added bridge IGMP snooping support to rhel6 2.6.32 kernel, and also to rhel6 bridge-utils. If you use mainline or custom Linux 2.6.32 kernel with el6 distro then you won't have that bridge IGMP snooping support in the kernel, and bridge-utils (brctl) will give errors like above.

There are two workarounds:

Use Xen dom0 kernel based on actual rhel6 kernel/patches, mayoung does have "xendom0" kernel available for el6 distros based on actual rhel6 kernel, with xen dom0 pvops patches added on top, so it includes bridge IGMP snooping support and the default el6 bridge-utils works OK without errors. See the end of this wiki tutorial page for links to xendom0 kernel rpms.If using custom dom0 kernel (xen.git xen/stable-2.6.32.x) then rebuild the el6 bridge-utils src.rpm and remove the IGMP snooping patch from the spec file:http://lists.xensource.com/archives/html/xen-devel/2011-02/msg00760.html .

Using graphical virt-manager to manage Xen on RHEL6

Some screenshots of using virt-manager with Xen on RHEL6 and installing Fedora 14 Xen PV domU. Note that you don't need (and probably shouldn't) run Xserver on dom0! You can use ssh X11 forwarding to run virt-manager on dom0 but display the virt-manager GUI on your local laptop/desktop. See the Fedora 13 tutorial link in the end of this page for more information about using ssh X11 forwarding.

Network setup details and troubleshooting

See Fedora13Xen4Tutorial for more information about virbr0 setup/configuration for NAT/DHCP, routing, firewall rules, et

Virtualization basics

Virtualization

Virtualization is a technique, which allows to share single physical instance of an application or resource among multiple organizations or tenants (customers). It does so by assigning a logical name to a physical resource and providing a pointer to that physical resourcewhen demanded.

Virtualization Concept

Creating a virtual machine over existing operating system and hardware is referred as Hardware Virtualization. Virtual Machines provide an environment that is logically separated from the underlying hardware.

The machine on which the virtual machine is created is known as host machine and virtual machine is referred as a guest machine. This virtual machine is managed by a software or firmware, which is known as hypervisor.

HYPERVISOR

Hypervisor is a firmware or low-level program that acts as a Virtual Machine Manager. There are two types of hypervisor:

Type 1 hypervisor runs on bare system.LynxSecure, RTS Hypervisor, Oracle VM, Sun xVM Server, VirtualLogic VLX are examples of Type 1 hypervisor. The following diagram shows the Type 1 hypervisor.

The type1 hypervisor does not have any host operating system because they are installed on a bare system.

Type 2 hypervisor is a software interface that emulates the devices with which a system normally interacts. Containers, KVM, Microsoft Hyper V, VMWare Fusion, Virtual Server 2005 R2, Windows Virtual PC and VMWare workstation 6.0 are examples of Type 2 hypervisor. The following diagram shows the Type 2 hypervisor.

Types of Hardware Virtualization

Here are the three types of hardware virtualization:

Full Virtualization

Emulation Virtualization

Paravirtualization

FULL VIRTUALIZATION

In Full Virtualization, the underlying hardware is completely simulated. Guest software does not require any modification to run.

EMULATION VIRTUALIZATION

In Emulation, the virtual machine simulates the hardware and hence become independent of the it. In this, the guest operating system does not require modification.

PARAVIRTUALIZATION

In Paravirtualization, the hardware is not simulated. The guest software run their own isolated domains.

VMware vSphere is highly developed infrastructure that offers a management infrastructure framework for virtualization. It virtualizes the system, storage and networking hardware.