Virtualization is a technology to use one physical server to appear like many to the outside world. This technology provides the ability to reduce cost from several different points:
- Power consumption decreases with fewer physical servers running
- Deployment and disaster recovery is simplified
- Reduced number of servers to maintain
- Scalable servers, permitting the migration of virtual machines from one physical server to another as load dictates
When a server is virtualized, it actually runs within another server, possibly side by side with several other servers and can be used for several different applications. The use of this technology has become increasingly popular because as power costs and server capacity have increased, price has decreased. With this extra computational power, systems are under utilized most of the time in a monolithic state.
Many times a company runs a stand-alone server for a particular proprietary vertical application. When replacing a server, there may be a desire to retire the physical box that the original application runs on. Enter virtualization: the new server is deployed with the hypervisor (virtual server system) and a new virtual machine is created within the system. Many times, the new virtual machine exists merely as a file on disk, thus migration to another physical server is as easy as moving a file.
The result: overall costs drop and data centers become more green.
How We Do It
Depending on the clients' needs we implement virtualized servers using Xen under CentOS (a free, de-branded version of RedHat Enterprise Server) or VMware ESXi. Each product has its advantages based upon functionality and hardware. Xen started as an community-driven project. It remains Open Source, supported by Citrix with their XenServer product. In comparison to VMware's ESXi which started out as ESX, a fee-based, licensed software and then transitioned into a free version. Both versions are free, but if advanced functionality is needed, it may be licensed for a fee.
Internally Zahler IT uses VMware after a period of time using XEN. the company hosts both CentOS and Windows servers in development and production systems on a single physical server. This enables a new server to be brought up within minutes, rather than hours using a baseline configuration which streamlines start-up on a new client project as well as giving us the ability to quickly test the impact of server changes.