====== Virtualization ======
====== tbd ======
  * http://www-01.ibm.com/support/knowledgecenter/linuxonibm/liaat/liaatsecstorotherdir.htm

If you want to change the default storage pool location, I don't know of other ways than manually editing /etc/libvirtd/storage/defauls.xml (shutdown libvirtd first and start it after) or linking the images directory to 
====== Libvirtd Image Location ======
  * https://ask.fedoraproject.org/en/question/9584/while-using-libvirt-how-can-i-use-a-location-other-than-varliblibvirtimages-to-store-my-images/
  * 
====== Managing qemu VMs ======
===== Using virt-manager =====

===== - Using virsh =====
Image Location:
    ls /var/lib/libvirt/
    boot/        dnsmasq/     filesystems/ images/      libxl/       lxc/         network/     qemu/       uml/         xen/

Restart libvirtd after manually delete image etc.
    service libvirtd stop

<code>
[dang@dai142 devstack-nodes]$ virsh -c qemu:///system list
 Id    Name                           State
----------------------------------------------------
 21    devstack-nodes_devstack-control running

[dang@dai142 devstack-nodes]$ virsh -c qemu:///system
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # list
 Id    Name                           State
----------------------------------------------------
 21    devstack-nodes_devstack-control running

virsh # exit


</code>

==== Save state of nested VMs ====

Save a running VM Guest with the command virsh save and specify the file to where it is saved.

Save the guest named opensuse11
    virsh save opensuse11 /virtual/saves/opensuse11.vmsav
Save the guest with the ID 37
    virsh save 37 /virtual/saves/opensuse11.vmsave
To restore it, use virsh restore:
    virsh restore /virtual/saves/opensuse11.vmsave

==== Troubleshooting vms ====
  * https://fedoraproject.org/wiki/How_to_debug_Virtualization_problems
  * https://unix.stackexchange.com/questions/33191/how-to-find-the-ip-address-of-a-kvm-virtual-machine-that-i-can-ssh-into-it
  * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/5/html/virtualization/chap-virtualization-managing_guests_with_virsh
  * https://serverfault.com/questions/627238/kvm-libvirt-how-to-configure-static-guest-ip-addresses-on-the-virtualisation-ho

    virsh list
    virsh net-list
    virsh net-list --all
    brctl show
    sysctl net.bridge.bridge-nf-call-iptables
    iptables -L -v -n
    ps -ef | grep dnsmasq
    ifconfig -a
    cat /proc/sys/net/ipv4/ip_forward
    service libvirtd reload    
====== Nested Virtualization with kvm intel ======
  * http://kashyapc.com/2012/01/14/nested-virtualization-with-kvm-intel/

Let us first ensure kvm_intel kernel module has nesting enabled. By default, it’s disabled for Intel arch[ but enabled for AMD -- SVM (secure virtual machine) extensions arch.]

 
    modinfo kvm_intel | grep -i nested
    parm:           nested:bool
    # 

Enable nested virtualization

     echo "options kvm-intel nested=1" | sudo tee /etc/modprobe.d/kvm-intel.conf

OR add boot option
    cat /etc/default/grub | grep CMDLINE
GRUB_CMDLINE_LINUX="rd.lvm.lv=vol0/swapVol rd.md=0 rd.dm=0  KEYTABLE=us quiet rd.lvm.lv=vol0/rootVol rhgb rd.luks=0 SYSFONT=latarcyrheb-sun16 LANG=en_US.UTF-8 kvm-intel.nested=1"

Verify

    cat /sys/module/kvm_intel/parameters/nested 
    Y
    systool -m kvm_intel -v   | grep -i nested
    nested              = "Y"
    # 

===== Enable Nested Virtualization Guest =====


The o/p of the above cmd has a variety of options. Since we need only vmx extensions, I tried the simple way by adding to the regular-guest’s libvirt xml(virsh edit ..) and started it.

    <cpu match='exact'>
      <model>core2duo</model>
      <feature policy='require' name='vmx'/>
    </cpu>

===== Start Guest with qemu-kvm =====
    ps -ef | grep -i qemu-kvm | egrep -i 'regular-guest-f18|vmx'
    qemu     15768     1 19 13:33 ?        01:01:52 /usr/bin/qemu-kvm -name regular-guest-f18 -S -M pc-1.3 -cpu core2duo,+vmx -enable-kvm -m 4096 -smp 4,sockets=4,cores=1,threads=1 -uuid 9a7fd95b-7b4c-743b-90de-fa186bb5c85f -nographic -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/regular-guest-f18.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/export/vmimgs/regular-guest-f18.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=25,id=hostnet0,vhost=on,vhostfd=26 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:a6:ff:96,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
    
    
===== - Paravirtualization =====
==== Xen ====
  * https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide


====== Libvirt ======
  * https://doc.opensuse.org/documentation/leap/virtualization/html/book.virt/part.virt.libvirt.html