By Gail Seymour
When you rent space on a server from a Web hosting company, do you ever stop to wonder what the server might look like? Many people imagine the server might resemble a desktop PC or that one of the rack-mounted servers in a bay might be allocated to their files, but for the majority of customers, this isn’t the case. Especially with hosts who use modern virtualization technology, there are a variety of ways your files might be stored.
- Rack-mounted servers 19 inches wide and housed in cabinets. Each server will contain its own power and network connections and its own cooling system.
- Blade servers are also sized to fit 19-inch rack mounts, but the cabinets they are housed in will provide power and networking connections and a cooling system for multiple servers, making more efficient use of space and energy.
- Modern mainframes don’t really look all that much different than rack-mounted or blade servers, collectively known as distributed systems. The cabinets are generally around the same size, and the component parts may be "hot swapped" without disrupting the server operation. The main differences between a modern mainframe and a distributed server cluster system are that the mainframe is more energy efficient and powerful and has inherent virtualization technology built in, whereas the distributed system relies on software virtualization.
Unless you are collocating your own equipment in a data center or have opted to lease a physical dedicated server from your Web host, the chances are increasingly likely that there will be some level of virtualization involved in your server setup. At its most basic, virtualization means configuring one or more machines to share resources and act as one or more "virtual" servers, where the resources shared do not correlate with the physical location on the machines involved.
So for example, a distributed system of physical servers may be configured to run as one large virtual machine, approaching the capabilities of a mainframe, or a mainframe may be configured to run as several smaller servers, each with their own allocated share of physical resources, and with their own partition on the hard drives and their own operating system.
To complicate matter further, these virtual servers may then be subject to further manipulation. The "virtual mainframe," for want of a better phrase, may run virtualization software to share these amalgamated resources between multiple virtual servers. So you might find, as an example, a bay of 20 physical machines scaled up to share resources, then divided into 50 virtual machines. The advantages of this are that the virtual servers created are better able to share processing power and other hardware components and better use can be made of capacity. It also means in the event of a processor failure, the chances of any of the customers’ websites being affected are reduced.
Web hosting has traditionally been defined by resource allocation:
- Shared Hosting
Refers to the fact that a hosting client rents space on a shared computer. The computer has a single operating system on a single partition, and multiple users share the resources. Although originally this meant security lapses on one account or high-resource usage could compromise the other users on the same server, virtualization technology and other software advancements mean that even on a shared hosting platform, user accounts can be effectively shielded from each other, and resource usage capped to prevent one client degrading the service provision to others.
A dedicated server originally meant just that, a server allocated for the sole use of a hosting client. Nowadays, it will more often mean the resources of a virtual server are allocated to an individual client, but what remains the same is that the client will have their own resource allocation, and other clients will not have access to the server on different accounts. They will be to create partitions and have control over the operating system and other programs installed.
- Virtual Private Server (VPS)
A VPS account bridges the gap between a shared hosting account and a dedicated server. With a VPS the client will have their own partition on the drive, offering increased security and separation from other clients, and will have some control over the operating system and programs installed.
With advancements in virtualization technology the distinctions between these account types are beginning to blur, and as more hosts move towards cloud computing, this trend is only likely to continue, especially between dedicated and VPS hosting accounts. One big advantage of this is the ability to increase the size of a virtual partition, making scaling up from one hosting package to another in increments much easier for clients, which in turn means they don’t have to pay for more resources than they are using.
Read the complete series:
Data Center Tour Part 1: Introduction
Data Center Tour Part 2: Meet the Staff
Data Center Tour Part 3: Physical Security
Data Center Tour Part 4: Redundancy
Data Center Tour Part 5: Servers
About the Author
Gail Seymour has been a website designer for more than 10 years. During that time she has won three design awards and has provided the content and copy for dozens of websites and more than 50,000 Web pages.