VIRTUALIZATION FOR SERVER CONSOLIDATION AND MANAGEMENT
Sean O’Connor
What is virtualization?
A general term used to refer to a collection of technologies which allow some degree of abstraction between the physical environment and the logical environment in which software runs. Allows a single physical system to exists as several logical systems (virtual machines), several physical systems to exists as one logical system (grid computing), or some combination there of.
How does virtualization work?
With Host-OS Without Host-OS
image from http://www.networkdictionay.com
image from http://www.vmware.com
Why use virtualization?
Workload consolidation. Hardware Abstraction. Secure Isolation between Virtual Machines. Redundancy can be achieved cheaply. Recovery, backup, replication, and migration can be performed much more easily. More advanced monitoring and management tools available.
Costs of virtualization
Each virtual machine adds significant resource overhead since each runs its own operating system. Virtualization software itself adds overhead. Generally each virtual machine must be licensed the same as a physical machine. Potentially complex migration and maintenance.
How to use virtualization for server consolidation and management
Take several under utilized physical servers and migrate them to several virtual machines. During this process try to limit each virtual machine to a single function or group of functions.
Create “Virtual Appliances”.
As the needs of any particular virtual machine exceed the host hardware migrate the VM to new hardware. Additionally install monitoring and remote management tools into the host OS and/or the virtualization software.
Why use virtualization for server consolidation and management
Allows for much more efficient use of hardware resources. Limits damage caused by any one service going down. Scales very well. Allows for virtual machines to be restarted remotely. Detailed statistics can be collected about each virtual machine’s resource use. Backups, recovery, replication, and migration of VMs are easier. Different virtual machines can be swapped out and deployed almost instantly.
Market/OSS Offerings
With Host OS
VMWare Server Microsoft Virtual Sever
Without Host OS
VMWare Server ESX Virtuozzo OpenVZ User Mode Linux Xen Solaris Containers
Sources
http://en.wikipedia.org/wiki/Virtualization http://www.kernelthread.com/publications/virtualiz ation/ http://www.techweb.com/encyclopedia/defineterm .jhtml?term=virtualmachine http://www.networkdictionary.com/software/vm.ph p