Red Hat Enterprise Linux 5 Administration Unleashed

APPENDIX BCreating VirtualMachinesIntroduced in Fedora Core 4 as a technology preview, virtualizationis now a supported feature of Red Hat EnterpriseLinux 5. Virtualization allows multiple operating systems (OS)to run on the same physical hardware inside virtual machines(VM). The operating systems can be the same OS, differentversions of the same OS, or different OSes.The benefits of virtualization include the following:. Better use of hardware. Instead of the systemresources sitting idle, they can be used for multipleOS instances.IN THIS CHAPTER. Virtualization SystemRequirements. Installing Virtualization. Setting Up the VM andInstalling the Guest OS. Introducing the virshCommand. Starting and Stopping theVirtual Machine. Modifying DedicatedResources. Performing Additional Actions. Managing VMs with the xmUtility. Less hardware. It takes fewer systems to run multipleOS instances.. Separation of services. Multiple services or applicationsdo not have to work together in one OS environment.If different library versions or kernelversions are required, it is easily achieved withVirtualization.. Separation of failures. If one VM goes down or needsto be taken offline for maintenance, the other VMsare not affected.. Separation of data. The filesystems for each VM arenot shared unless file sharing is explicitly configured.Users of one VM cannot view the data on a differentVM, allowing an administrator to configure VMs fordifferent groups who can share data among themselves.Also, if one VM is compromised, the data onthe other VMs are safe from the security breach.. Easier recovery. If a VM goes down, the host systemand other VMs are still up and running so the failedVM can be recovered.