VirtualBox is a free, open-source hypervisor from Oracle. It has performance on par with VMware and is very mature. We have two virtualization servers which run VirtualBox on top of CentOS, biovbox and biovboxtest.

• VirtualBox homepage
• Tips to optimize Linux guests and hosts

Guest operating systems are not like host operating systems. These settings are generally regarded as improving the performance of guest virtual machines.

• Set the IO scheduler to noop:
  • Edit the grub command line to set the default IO scheduler, usually in /etc/default/grub: elevator=noop
• Install guest additions (VirtualBox or VMware)
• Run a virtual machine-specific kernel:
  • Ubuntu: linux-image-virtual
• Mount filesystems with noatime in /etc/fstab

If your guest is using bridged networking you MUST use this command to allow other users to use the host's physical network card. Make sure your virtual machine is shut down and then run this command:

VBoxManage setextradata MyMachine VBoxInternal/Devices/pcnet/0/LUN#0/Config/RestrictAccess 0

Each and every VM using bridged networking must use this command. If you are seeing errors like VERR_PERMISSION_DENIED regarding the network interface, this is the cause!

As of VirtualBox 3.1.2 this is still a known issue.

If your guest OS is using NAT for networking and you want to access services like Apache or SSH, you will need to enable port forwarding. There is no GUI for this in VirtualBox, but you can use VBoxManage setextradata to make the required changes. If you want to SSH to your VM, for example:

$ VBoxManage setextradata Ubuntu "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/HostPort" 2223
$ VBoxManage setextradata Ubuntu "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/GuestPort" 22
$ VBoxManage setextradata Ubuntu "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/Protocol" TCP

Then you can log in to the VM from your own computer using the port you've forwarded above:

$ ssh -p 2223 username@172.26.0.200

$ VBoxManage list vms

$ VBoxManage list runningvms 

Either shut down or "save state" for any running VMs. First, find any users who have "headless" VMs:

# ps aux | grep -i VBoxHeadless
jmagochi  4939  3.9  3.5 759372 72268 ?        Sl   Oct05 402:13 /usr/lib/virtualbox/VBoxHeadless -s nobu
jmagochi  4991 12.5  3.2 621588 67632 ?        Sl   Oct05 1281:41 /usr/lib/virtualbox/VBoxHeadless -s lims
aorth    18431  9.7  1.7 998940 36160 ?        Sl   Oct11 129:54 /usr/lib/virtualbox/VBoxHeadless -s b0237553-9653-4461-bd0e-d4d316c16d4f -v off

As the user who owns the VM, save the VM's state:

# su - jmagochi
$ VBoxManage controlvm nobu savestate
$ VBoxManage controlvm lims savestate
$ exit
# su - aorth
$ VBoxManage controlvm b0237553-9653-4461-bd0e-d4d316c16d4f savestate
$ exit

# yum update VirtualBox-3.2

# su - jmagochi
$ VBoxHeadless -s nobu &
$ VBoxHeadless -s lims &
$ exit
# su - aorth
$ VBoxHeadless -s b0237553-9653-4461-bd0e-d4d316c16d4f -v off &