What is VPS, and Do I Need It?

What would you do if your website out grow your shared hosting plan, but you can’t afford to get a private server to host your site on? Going for the Virtual Private Server could be a solution.

So what is a virtual private server (VPS)? It is more than a shared server and less than a dedicated server. A VPS simply put is, a server that runs inside another server. Each VPS looks, feels, and acts like a dedicated server but shares the same hardware. Think of it as a multi-tenant dwelling or luxury condo. Each apartment has its own private amenities within the same larger building.

Most hosting provider of VPS will slice up a physical server into virtual or "private," systems. Each private server has its own unique file system, disk space, user space (including virtual root), process space, CPU, bandwidth, and memory allocations:

• Performance Isolation: Heavy traffic or CPU load has no affect on other private servers on the same box, but there are limits on CPU, Memory, and Process.
• Functional Isolation: A VPS does not share applications or services with other VPS, nor do they share the same file system. VPS are invisible to each other and do not share processes.
• Fault tolerance: Errors or faults in one private server do not affect others.
• IP Addresses: Each private server has it's own set of IP addresses and network stack.

What do you get?

• Root access to individual VPS: This allows you to run your own applications and fully manage your VPS as you would on a private server.
• Guaranteed QOS/SLA: Memory, CPU, bandwidth, disk space, and uptime.
• Enhanced Security: Private servers do not share disk space, TCP/IP stacks or processes.

Why do you need it?

Users would want a dedicated server for the following reasons:

• Control: So they can install and run their own applications
• Security: To ensure that they will never have to share the same space with other customers
• Isolation: To eliminate the risk of downtime due to others mistakes, attacks/hacks or faulty scripts
• Performance: Their site is growing and needs more resources.

All of these are valid reasons to graduate to a dedicated hosting account. However, most of these sites only utilize a very small portion of the dedicated machine: as little as 5% or less, which is where a VPS comes in. As you know the VPS gives you all the benefits of a private server, but now you can share a physical server and still have the same guarantees of a private server: for a fraction of the cost.

When you buy a VPS you are paying for a slice of the server. You get a set of QOS/SLA values that can expand as you grow. Any of these values can be increased on the fly, and activated with a simple reboot of the VPS.

An Example VPS Plan:

• 5% CPU: Minimum Guarantee, you can't get any less but can burst to 100%
• 5% Bandwidth: Minimum Guarantee, you can't get any less but can burst to 100%
• 1GB Disk: Maximum Allocation but can be expanded
• 128MB RAM: Maximum Allocation but can be expanded
• 256 Processes: Maximum Allocation but can be expanded

Choosing a VPS Hosting Company

How do you choose your desired VPS Company? Here is quite a few pointers to look out for:

Know the details of your hardware resources:

• What are the specifications of the host server? (RAM, CPU, Network throughput, etc.)
• How many VPS instances are run on the host server that you'll be on? This is important because you are effectively sharing the host server's resources with these other VPSes.
• How is resource contention handled? In other words, what happens if all the other VPSes on your host server are running CPU/RAM-intensive processes? Do you have a dedicated minimum amount of RAM/CPU/Network usage? If so, how much?

Know the details of your Virtualization technology:

• What's the underlying OS: Linux, FreeBSD, Windows? If Linux, what distributions are offered?
• Are they using User Mode Linux, QEMU, or XEN? Why was that specific technology chosen?
• How are hardware upgrades handled? Let's say you start out with a basic plan that offers 64MB dedicated RAM and 2GB disk space. Six months from now, you realize you need more RAM and more disk space. What are the additional costs and what is the procedure for allocating the additional resources?

Know the details of your Web hosting company. These are the more traditional questions that apply across the board when you're choosing a Web host of any sort:

• What kind of support is offered (phone, email, IM, IRC - 24/7?)
• How long has the company been in business?
• What is the company's client retention rate?
• How much downtime have they experienced in the last 12/24 months?
• What backup/redundancy measures do they have in place?

Prices range from $20 per month at the low end to more than $100 per month for higher end systems, but beware: price isn't always an indication of more features or better service. If you're still wondering whether a VPS hosting plan is right for you, it may be worth starting at the lower end (potentially a 64MB RAM with 2GB disk space VPS). You can always expand from there -- just be sure to choose a hosting company that can accommodate the expansion you have in mind. If you need significantly more hardware resources, co-location is the way to go.

Jumping from a shared hosting account to a private server is like going from flying a single engine Cessna to a Jumbo 747. They do the same thing, get you from point A to B, but are very different in terms of their operating environment and required skill set. If you desire the speed, luxury, comfort and security of a Jumbo Jet but don't need to fly as high or carry as many passengers, then a VPS is right for you.