Shared web hosting

Posted Posted by Patrice Guay in Web hosting     Comments 1 comment
Feb
9

shared hostingA shared web server is generally a slice of a physical server along with a control panel to simplify the management of your web solution. The available resources of the physical server are shared between the different guests. The ratio of resource allocation between the guests is fluctuating according to offer and demand. This entry-level solution for web hosting is offered at a low cost but has several limitations. Limited scalability and variable performance due to host resource consumption are the main drawbacks of this web hosting solution.

Cost

The cost of a shared web server is the lowest in the web hosting line of products. It is usually below 10$ per month. Some web hosting companies are giving huge discount for long term contracts. However, opting for a long term contract has several drawbacks. First, technology is evolving rapidly. If the physical server is not maintained and updated, you will end up having an outdated stack of applications for your web solution. Secondly, your needs may evolve to a point where a shared web server is no longer a viable option. Finally, the control panel offered to manage your guest may not be adequate for your particular needs.

Resource allocation

The physical server is dynamically allocating the following resources to the shared web servers:

  • CPU
  • memory (RAM)
  • disk space
  • disk I/O
  • bandwidth

CPU time of the physical server is shared by its guests. Nowadays, multi-core CPU can provide physical servers with a large pool of processing power. Memory (RAM) of the physical host is also an important element since it provides caching space for regularly accessed data.

Disk space is often advertised as an unlimited resource on a shared web servers. The reality is different. The size of hard drives grew rapidly during the last years and a physical server with a storage capacity of a few terabytes is no longer expensive, especially if it is built with SATA drives. Web hosting companies will oversell their available storage space and count on the fact that a majority of customers only use a small fraction of disk space on their shared web server. For example, let’s imagine a physical server hosting 1010 guests. The first 1000 guests are using 100MB of disk storage each while the last 10 guests are using 10GB each. While every guest can use up to 10GB of storage according to their contract, only a fraction is doing so. As a result, the 1010 guests are using a total of 200GB.

Another important resource of the physical host is disk Input/Output. I/O performance is related to the speed at which data can be written and retrieved from the disks. While hard disk technology improved greatly in regards to disk space, I/O performance has seen little improvement during the last years especially for low budget solutions. Cheap storage is still built on SATA 7 200 RPM drives. While the drives grew larger, they still spin at the same speed and have similar I/O performance. Sharing this scarce resource with a multitude of other guests results in a very low disk I/O performance on shared web servers. If your application is database intensive or requires many read and write operation to small files, your disk I/O requirements will be too high for a shared web hosting solution.

Bandwidth is also a limited resource on a shared web server. The physical host is connected to the Internet through network equipment (network card, switches, routers) having fixed specifications. The available bandwidth is thus shared between the guests. Unlimited bandwidth often means you can upload your content without having to worry about a contract limitation for your monthly total usage. However, the actual connection speed between your server and the Internet is not guaranteed. Your connection speed will depend on the other guests usage.

Uptime

Serious web hosting company are keeping a close eye to resource utilization on their physical servers. When the resource consumption of a particular guest is seriously impacting the performance of its neighbour guests, a few solutions are available:

  • move the problematic guest to a less crowded physical server
  • suspend the problematic guest
  • leave the problematic guest return to normal activity by itself
  • upgrade the problematic guest to a VPS or a dedicated server solution

Moving the guest to another physical server is not always possible. If it is, the shared server will suffer some downtime while it is being migrated. When the migration of the problematic host is not possible, its suspension is often chosen as a solution. The shared server will then experience downtime until action is taken by its owner.

Leaving the problematic guest return to normal activity by itself is also a possible solution or the symptom of a lack of monitoring from the web hosting company. While the problematic guest is consuming too much resources, other guests of the physical host will experience difficulty to serve web pages to their audience.

A suspended account may have to migrate to an higher end web hosting solution. Sometimes, your web application and its popularity requires too much resources to be hosted in a shared environment. The migration toward a dedicated or a virtual private server will likely solve your issue.

There are several other factors that will influence the uptime of your web solution:

  • application stability
  • physical host hardware stability
  • network uptime
  • electrical power uptime
  • air conditioning uptime
  • datacenter operator skills

The stability of your web application is your sole responsibility if you chose a shared web hosting plan without support. If you decide to add a support plan for your shared web server, the web hosting customer service will be able to help you solve your application issues up to a certain point. Verifying the competence and diligence of the customer service is important if you need support for your web hosting solution.

The hardware stability of the physical host is also a relevant factor for the uptime of your web solution. If the physical host hardware fails, it will have to be replaced in order to restore your web presence. Disk failure is a critical event and should be planned for by taking regular backups of your sensitive information.

If the network connection between the physical host and the Internet is broken, your web solution will be unavailable for your visitors. Unless you made a modification to the network parameters of your shared web server, a network connectivity problem is usually the symptom of a problem in your web hosting company network infrastructure. Verifying the uptime of your web hosting company homepage on Netcraft may give you a good indication of their network infrastructure health.

The uptime of the electrical power delivered to the physical host will also influence the global uptime of your web solution. A serious web hosting company will use uninterruptible power supply (UPS) and generators to maintain electrical power for the server and their network infrastructure during blackouts.

Air conditioning is also a crucial element for datacenters with a high density of equipment. A failure of the air conditioning system will most likely cause the physical host to overheat and shut down. This type of outage is critical since the overheat of the physical host may break some key components like the CPU, the disks or the motherboard of the physical host.

Error during manual maintenance by the datacenter operators can cause downtime to your shared web server. A datacenter with unlabelled servers or network equipment is most likely exposed to such human errors.

Monitoring probes are a great tool to continuously check for the uptime of your web solution. The support plan for your shared web server may already include such a service. In case of a downtime, the web hosting customer service and yourself could be advised automatically. If your support plan does not include such a service, you should seek this service elsewhere to protect your web presence and reduce the length of downtime.

Scalability

A shared web server does not scale well. If your resource consumption goes too high, you will most likely be asked to move toward an higher end hosting solution.

Support

There is basically four layers of management on a web hosting solution:

  • datacenter layer: electricity, cooling, physical security, fire protection, building maintenance
  • networking layer: Internet connectivity, activity monitoring, IP addresses provisioning
  • server equipment layer: server installation, cabling, hardware maintenance
  • application layer: OS installation, OS updates, application installation and configuration, monitoring

For a shared web server, the datacenter, networking and server equipment layers all fully supported by the web hosting provider. The application layer is most likely supported through a control panel interface. This control panel is used to ease the management of your server. Mail accounts, web applications, databases and user management are simplified by the use of a well designed control panel. In case of problem, the web hosting company will offer support for basic control panel operations.

Conclusion

Shared server is the entry-level solution for web hosting. For a low monthly fee, you will share the resources of a physical server along with a multitude of other guests. While this solution is sufficient for low volume websites, it will not scale up in case of an increase of your audience.

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