View source for KVM

== Introduction ==
[Needed: disambiguation page for KVM See: [http://en.wikipedia.org/wiki/KVM Wikipedia: KVM] ]

Kernel Virtual Machine - KVM is an Open-Source Virtualization package for Linux.

See: [http://www.linux-kvm.org www.linux-kvm.org]

Related page(s): [[OpenVZ]]
=== To Do ===
This page needs:
* Intro section with pointers to useful docs
* Installation Instructions as needed
* Cookbook section

== Documentation ==
* IBM Quick Start / Guide http://pic.dhe.ibm.com/infocenter/lnxinfo/v3r0m0/topic/liaai/kvminstall/liaaikvminstallstart.htm
* Documents http://www.linux-kvm.org/page/Documents
* KVM How-To's http://www.linux-kvm.org/page/HOWTO

== Creating New KVM CentOS VMs ==

1. create logical volume for new VM's base filesystem (/boot, 1G swap, /)
<pre>
lvcreate -L 10G -n vm.$name.root main
</pre>

2. clone base VM into the new logical volume
<pre>
virt-clone -o centos_base -n $name -f /dev/mapper/main-vm.$name.root
</pre>

3. create cdn logical volume
<pre>
lvcreate -L 500G -n vm.$name.cdn main
</pre>

4. create additional swap volume if needed (base VM has 1G swap, an additional 4G is recommended for memory intensive applications)
<pre>
lvcreate -L 4G -n vm.$name.swap main
</pre>

5. edit VM config.  adjust memory, processors, etc. as necessary.  add cdn (as vdb) and swap (as vdc) drives.

<b>NOTE:</b> there's not a lot of memory to go around, be conservative.  VMs support memory 'ballooning' which is a way to give additional memory on-demand and then reclaim it when it's freed.  &lt;memory&gt; specifies the maximum amount of memory that the VM can use.  &lt;currentMemory&gt; specifies the amount of memory that the VM boots with.  If the two are the same, then memory ballooning is disabled.  If $memory is greater than $currentMemory, the VM will start off with $currentMemory and be able to balloon on demand up to $memory.  If the application is memory intensive, configure it with a small-ish $currentMemory and a larger $memory so that memory can float between VMs as needed.  Try to keep VM applications memory efficient.

<b>ALSO:</b> there are also so many processors, so be conservative there as well.  Don't configure more than 2 processors for a VM.

<pre>
virsh edit $name
</pre>

6. boot VM
<pre>
virsh start $name
</pre>

7. log into VNC console as root

8. create cdn partition and filesystem, mount
<pre>
printf "n\np\n1\n\n\nt\n83\nw\n" | fdisk /dev/vdb
mkfs.ext4 -L /cdn /dev/vdb1
printf "LABEL=/cdn              /cdn                    ext4    nosuid,nodev,noatime 1 1\n" &gt;&gt; /etc/fstab
mount /cdn
</pre>

9. create swap partition and initialize
<pre>
printf "n\np\n1\n\n\nt\n82\nw\n" | fdisk /dev/vdc
mkswap -L SWAP-vdc1 /dev/vdc1
printf "LABEL=SWAP-vdc1         swap                    swap    defaults        0 0\n" &gt;&gt; /mnt/etc/fstab
</pre>

10. fix eth1 configuration
<pre>
# on VM host, get eth1 mac address from output of:
virsh dumpxml $name

mv /etc/sysconfig/network-scripts/ifcfg-eth1.bak /etc/sysconfig/network-scripts/ifcfg-eth1

# replace mac address with that obtained from virsh dumpxml, replace IP with correct IP for the VM
vi /etc/sysconfig/network-scripts/ifcfg-eth1
</pre>

11. remove unneeded eth0 backed up config
<pre>
rm /etc/sysconfig/network-scripts/ifcfg-eth0.bak
</pre>

12. correct the VM IP in the BGP config
<pre>
# correct route-id IP, should be the VM's IP
vi /etc/quagga/bgpd.conf
</pre>

13. set the VM's host name
<pre>
# change the HOSTNAME value
vi /etc/sysconfig/network
</pre>

14. fix home directory location
<pre>
mv /home /cdn/users
ln -s /cdn/users /home
</pre>

15. reboot

16. log in as root via ssh

17. application-specific configuration (e.g. users, application packages, etc.)