| Virtual Private Server |
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| Wednesday, 07 July 2004 11:54 |
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The practice of partitioning a single server so that it appears as multiple servers has long been common practice in mainframe computers, but has seen a resurgence lately with the development of virtualization software and technologies for other architectures. A virtual private server (VPS, also referred to as Virtual Dedicated Server or VDS) is a method of splitting a server. Each virtual server can run its own full-fledged operating system, and each server can be independently rebooted. Virtual Private Servers (VPS) Overview: In a paravirtualized environment, the guest is aware of the hypervisor and interfaces directly with the host system's resources, with the hypervisor implementing real-time access control and resource allocation. This results in near-native performance since the guest sees the same hardware as the host and can thus communicate with it natively. UNIX-like systems, such as Linux, some variants of BSD, Plan9, and OpenSolaris are currently known to support this method of virtualization. However, installing operating systems as paravirtualized guests tends to require more knowledge about the operating system in order to have it use special hypervisor-aware kernels and devices. The physical server typically runs a hypervisor which is tasked with creating, destroying, and managing the resources of "Guest" operating systems, or Virtual Machines. These guest operating systems are allocated a share of resources of the physical server, typically in a manner in which the guest is not aware of any other physical resources save for those allocated to it by the hypervisor. The Guest system may be fully virtualized, paravirtualized, or a hybrid of the two. In a fully virtualized environment, the guest is presented with an emulated or virtualized set of hardware and is unaware that this hardware is not strictly physical. The hypervisor in this case must translate, map, and convert requests from the guest system into the appropriate resource requests on the host, resulting in significant overhead. Almost all systems can be virtualized using this method, as it requires no modification of the operating system, however a CPU supporting virtualization is required for most hypervisors that perform full virtualization. Some examples of paravirtualization-capable hypervisors are Xen, Virtuozzo, Vserver, and OpenVZ (which is the open source and development version of Parallels Virtuozzo Containers). Hybrid or partial paravirtualization, is full virtualization, but in which the guest uses paravirtualized drivers for key components such as Networking and Disk I/O, resulting in greatly increase I/O performance. As such, it is a common solution for operating systems which cannot be modified (for various reasons) to support paravirtualiztion. VPS Used: Virtual private servers bridge the gap between shared web hosting services and dedicated hosting services, giving independence from other customers of the VPS service in software terms but at less cost than a physical dedicated server. As a VPS runs its own copy of its operating system, customers have superuser-level access to that operating system instance, and can install almost any software that runs on the OS. Certain software does not run well in a virtualized environment, including firewalls, anti-virus clients, and indeed virtualizers themselves; some VPS providers place further restrictions, but they are generally lax compared to those in shared hosting environments. Due to the number of virtualization clients typically running on a single machine, a VPS generally has limited processor time, RAM, and disk space. Due to their isolated nature, VPSs have become common sandboxes for possibly-insecure public services or update testing. For example, a single physical server might have two virtual private servers running: one hosting the production-level (live) website, and a second which houses a copy of it. When updates to crucial parts of software need to be made, they can be tested in the second VPS, allowing for detailed testing to be conducted without requiring several physical servers. Virtual private servers are also sometimes employed as honeypots, allowing a machine to deliberately run software with known security flaws without endangering the rest of the server. Multiple honeypots can be quickly set up via VPS in this fashion. The Advantages Of Virtual Private Servers Versus Shared : For a long time the only platform choice in hosting was between low-cost shared servers or high-cost dedicated servers. Now there is a viable third choice – mid-priced Virtual Private Servers (VPS). Virtual is the key word A VPS offers many of the advantages of a dedicated server whilst physically running in shared hardware. This is achieved through smart virtualisation software that creates and manages a number of ‘virtual servers’ within the shared hardware. Each ‘virtual server’ appears to the customer’s applications, databases and so on as if it really was a dedicated server, with a pre-set memory size, disk size and network bandwidth. It even allows the customer to fully configure the environment for their specific application and security needs. The virtualisation software then protects that ‘virtual server’ from the actions of all other ‘virtual servers’ that are operating on the same physical hardware. So, should another customer’s application go ‘rogue’ because of a coding error or become swamped with internet transactions, the other ‘virtual servers’ would carry on as normal. Even a major crash within one ‘virtual server’ won’t affect the others. The virtualisation software that makes VPS possible has become very advanced indeed and recently we’ve seen the entry of Microsoft into the market with their Hyper-V product. This is strong evidence that the virtualisation approach is fast becoming mainstream, not just for hosting companies like us, but also for large IT users looking to improve the efficiency of their hardware utilisation. The advantages of VPS over shared servers The biggest drawback of using a shared environment for your websites or applications is the impact of on your system’s performance and reliability from those that you share with. All you need is one of the other user’s applications to crash badly and the whole shared server would stop and need re-booting. Similarly another user’s website becoming very popular would slow the system down for your applications as they would consume a disproportionate amount of the shared system resources. Under the VPS approach these issues just go away. It’s as simple as that. The virtualisation software protects each ‘virtual server’ from the others and isolates the key resources that have been configured. So if one VPS has been configured with 512Mb of RAM, then it always has that amount of memory available to it regardless of what other ‘virtual servers’ are requesting (even though the total pool of RAM is shared amongst all ‘virtual servers’). It is this protection and isolation that justifies the use of Private in the VPS name. The advantages of VPS over dedicated servers. Before virtualisation software became available the only alternative to the performance ‘lucky dip’ of shared servers was dedicated configurations. This required the hosting provider to purchase and configure new hardware for each customer. This in turn meant a substantial capital investment upfront by the hoster and the rapid consumption of their data centre space, power, network connections and so on. Because of this the fee for dedicated servers has been set high. The VPS concept changes the hoster’s cost model considerably. Now, the hoster can provide a near-dedicated quality of service using shared hardware, which reduces the consumption of their data centre racking, power and network connections. This cost reduction is passed onto the customer through reduced fees. Another cost-related issue that using VPS technology changes considerably only comes into play after a number of years of use … hardware refresh. In the traditional dedicated server model, when the server hardware reached a certain age (often three years) it made sense to refresh it for new hardware. This would reduce the risk of failure as well as allowing the customer to take advantage of improvements on processors speeds and so on. The idea of refreshing the hardware after a period of continuous still holds true for a VPS, but the big difference is in who pays. For a dedicated server, the full cost of the replacement hardware was borne by the customer through the fee levels, sometimes including a new set-up fee as well. Whereas in the VPS model, the cost is spread over a number of customers, thus the fees can remain low throughout multi-year contracts even when hardware refresh is included. Conclusion: Virtualisation is being rapidly embraced by both hosting companies as well as large IT using organisations. As an approach it makes strong financial as well as technical sense and even reduces carbon footprints. There will, of course, still be complex computing needs for which true dedicated servers are a necessity. But for many commercial computing needs virtualisation offers significant resilience and performance improvements over using shared servers with no technical disadvantages. VPS has definitely come of age. If you’d like to chat through your hosting needs and see whether a VPS solution would be of benefit, just give us a call. Clearly, web hosting basically relies on the needs and requirements of the customers. VPS hosting is suggestible for sites with lot of interactivity - sales, information gathering, data transmission, etc. High-flown businesses need faster downloads and sales interaction to satisfy their customers and attract their potential customers. VPS can be a reliable service for them. However, there's a large section of aspiring businessmen who wish to start business on the web from the scratch, but have a low budget. Shared web hosting provides them a platform to establish their website. Shared Web Hosting Versus Virtual Private Server : Pros and Cons Web Server OS and software application Shared web hosting: Essentially shared web hosting servers are designed to accommodate several web hosting customers. They host a single operating system and software applications on that server that is shared by different customers. VPS web hosting: The servers are unique complete operating system for that particular VPS server. All the other software application and add-on tools are specially installed for individual web hosting customers. VPS enables web hosts to host numerous on-line companies on a single, physical host server. With VPS you still share the same physical hard drive as other sites. However, each virtual server is kept isolated from its neighbors. Private Email Server & IP Address Shared web hosting: For the start up companies running on budget shared web hosting offers a cheap solution. This is why there are a large number of shared web hosting user. They share the same email server and IP address. VPS hosting: It provides a private email server for the individual customers and a unique IP address for the VPS server as well. Most of the large businesses require their emails coming from unique IP address. This allows the them to deliver the emails faster and spam filter quality gets higher as well. Resources Shared web hosting: In shared hosting the customers are restricted with resources and must share it with literally hundreds of other websites. Now all of these website compete with each other for the resources of the server. VPS web hosting: Leasing a VPS allows you the ability to have more resources allocated to your websites. With VPS a set amount of memory, and hard drive space is allocated to the customer. This is especially important for websites that are resource intensive. Customization Shared web hosting: As there is a shared system there are no customization for operating system or software. VPS hosting: Users can setup their required operating system and software. They can use their preferred version of PHP and MYSQL and have full root access to the partition. Security Policy Shared web hosting: Prime concern for shared web hosting is security. Shared web hosting server used by several customers and they share the same email and IP address, which makes it highly vulnerable. The email (POP/SMTP/IMAP/Web Mail) must be accessible through both secure and standard connections. VPS hosting: It adopts a customized security policy. This allows the user to control how the VPS is accessed and when. In VPS hosting the users access their email through a secure socket layer (SSL) connection. The system is more secured as it ensures that the logins and passwords are encrypted and it might prevent hackers from obtaining that information while in transit. Anti-virus Scanning Shared web hosting: They provide anti-virus solution to protect against hacking provides a email spam filter. VPS hosting: The services provide individual on server anti-virus scans that ensures spams with viruses and malware will not affect the server. Pricing Shared web hosting: This is the cheapest web hosting solution with prices. VPS hosting: Although not as low as shared hosting, price for VPS hosting is more affordable than dedicated server. This considerably reduces the expense required to get multiple resources and network by providing a physical server that is virtually partitioned. Top VPS Hosting Companies VPS hosting offers the advantage of a dedicated server at a fraction of the price. Virtual Private Servers and virtual hosting are exciting options for individuals and businesses looking for significant control and disk space. Hosting-Review.com’s top 10 List below offers the information you need to choose the best virtual web hosting service for you. Gate.com + Expert 24/7/365 Phone Support + The Best Value in VPS Hosting. Compare Price & Features + $29.99/mo. - First Month Free - No Contracts Required + Choose from 4 Plans available with Windows or Linux Operating Systems + 25 GB Disk Space, 1 TB Transfer & More! 1and1.com + 90-day money back guarantee + Premium Software Suite + SSL included with select packages + Unlimited MySQL databases + 24/7 phone and email support + Dedicated IP address godaddy.com + Choose a preconfigured plan or build your own + Free setup & SSL certificate + Free Google AdWords & Microsoft adCenter Credits + FTP backup available + 24x7 email, telephone and web-based tech support + 24x7 physical security and network monitoring lunarpages.com + Free IP Address & Domain + Free ParallelsR Plesk Panel + FTP backup available + 24/7/365 Support + 99.9% Uptime + Managed Hosting options Available! + 512MB RAM guaranteed + 1000GB Bandwidth + Windows Or Linux, Fully Customizable. eboundhost.com + Fully independent environment + Choice of Plesk-30 or cPanel-Unlim control panel + Resource monitor + Tech Support on-site 24/7 + Extremely powerful machines ixwebhosting.com + Expert 24/7/365 toll-free phone and chat support + 30-day money-back guarantee + 3 plans to choose from, starting at $29.95 a month + US-based call centers + All data centers owned by IX Hosting inmotionhosting.com + Regular, automated, secure backups + Individual custom Firewall + 90 day money back guarantee + SSH Access with optional Root Access + Your choice of data center and max speed zone options. provps.com + Multiple FileSystem types + Multiple distributions - choose from at least 10 (including CentOS and Fedora) + Reverse DNS + Dual Xeon hosts. easycgi.com + Dedicated IP addresses + 24/7 phone support and live chat + Advanced ticket system + Same day FREE setup + 30-day money back guarantee + 99.9% uptime guarantee |
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