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1. What is Hybrid Hosting?
Hybrid hosting employs a combination of dedicated servers and cloud servers, to get the benefits of both. Before we discuss in detail the pros and cons of hybrid hosting, let’s define each component and understand how it works.
Hosting is done on servers, computers with varying number/amount, quality and speed of processors (CPU), memory (RAM) and storage (hard drives, RAID array or network based storage), that connect to the internet using networking gear (at speeds of 10 to 1000 Mbps). Traditional hosting is split between shared hosting and dedicated hosting. In shared hosting, each server contains dozens to hundreds of users who shared its resources. With dedicated hosting, a client has the server all to him/herself. Dedicated servers can be owned by the client and hosted in a data center (colocated servers), owned by the data center but managed by the client (dedicated servers), or owned and managed by the data center (managed-dedicated). The advantage of a dedicated server is higher performance, security, stability and compliance with privacy requirements of credit card companies or the government health authorities. Shared hosting’s advantage is its lower cost.

Cloud servers, and cloud hosting, are a more recent development, based on advances in virtualization technology which makes it possible to isolate individual servers while deploying on shared hardware. Cloud hosting has a number of advantages, including the ability to clone servers, and to quickly and easily scale up as demands increases, and scale back when the load subsides. Many providers charge for cloud servers using a utility, or pay-as-you-go, model, in which customers only pay for the computing resources they use.

Clouds servers can be a part of a public (external) cloud, a community cloud or a private (internal) cloud. A public cloud is the ‘traditional’ cloud, such as Amazon’s EC2 servers or S3 storage – resources are provisioned over the internet from an off-site third party, which charges according to a utility model. A community cloud is a smaller cloud that is hosted by a third party and is used by several (affiliated) organizations with similar requirements, such as a city using Google apps for its various department. This setup, where an external cloud is walled off for use by a single entity, is also called a ‘virtual private cloud’. A private cloud is an emulation of cloud computing on a private network, using virtualization technologies and cloud management tools, but deploying in the data center and using hardware of the customer, not a third party host.

Hybrid hosting uses a combination of dedicated hosting (either at an ISP’s data center or in- house) and external cloud hosting to get the benefits of each. A newer hybrid model is a combination of private (or virtual private) cloud and public cloud. Let’s then look at the benefits – and disadvantages – of the different hosting methods.

The Pros and Cons of Different Hosting Types
Shared servers are cost effective, since a single server is divided between many users. The host benefits from loading as many users as the server can take, resulting in higher, more efficient, server usage. The disadvantage of a shared server is that a single user with a buggy or hyperactive site can degrade performance, often catastrophically, for all other users. In addition, security is only as good as its weakest link, and one clueless user who compromises or crashes the server can lead to loss of data or business for all other users.

Dedicated servers have a number of things going for them, most importantly stability and security. They are a familiar entity, battle-tested, hardened and time proven. They are under the total control of their owner, who can modify them in any way desired. They can be used to host legacy applications on older operating system, or to deploy the latest cutting edge technology.

On-premises dedicated servers have the added advantages of physical access and control. Colocated dedicated servers, still under their owner’s physical control, benefit from the higher availability, fast and stable connectivity, and quality infrastructure of a data center, at competitive prices. Managed dedicated servers, serviced, administered and backed up by the ISP, free the owner’s technical staff to focus on their core business – software development, on-line sales, marketing and business development.

The single ownership of a dedicated server means no interference from other users, leading to smoother, more predictable and stable performance. The server owner can install the necessary tools and implement the proper policies to comply with different regulations and standards, and is not exposed to the consequences of other users’ mistakes. Applications that make intensive use of I/O, such as databases, perform better on a dedicated server.
Dedicated servers have a number of shortcoming as well. Unmanaged servers require server administration and security expertise, and substantial resources for monitoring and updating the server software. Dedicated servers do not scale well. If the server is not up to the task, stronger (or additional) servers have to be procured, time consuming even at a data center. Dedicated servers can not handle spikes in load very well – they max out at their specs. To accommodate load spikes requires keeping additional servers, ready to be put on line when the need arises.
Dedicated servers typically use only a small portion of their resources (5-10%) at any given time. The higher dollar equipment layout and the lower usage adversely affect dedicated servers’ return on investment.

Cloud servers, due to the unique nature of virtualization technologies, can be provisioned in minutes. They can be automatically created on demand, and scaled up ‘indefinitely’ to provide additional processing power, memory, bandwidth, or storage space as needed. The payment model of a many hosted cloud servers is such that only used resources are charged for, lowering infrastructure costs and lowering waste of server cycles, memory or storage devices.

On the down side, cloud servers software stack is limited, their stability and security are not well established, nor have all the bugs been ironed out of them. Cloud servers, though virtualized, are still using shared hardware, leading to potential QoS (quality of service) issues, which are only now beginning to be addressed with SLA’s. Finally, cloud servers are better for serving web pages, providing storage space and content delivery of large multimedia files, but are less amenable to intense I/O demands of a database server or other I/O intensive applications.
The supposed advantage of a hybrid hosting is that one can maintain the stability, security and compliance of dedicated servers, while taking advantage of the scalability, flexibility, and rapid provisioning of cloud servers to handle demand spikes, leading to cost savings and better overall performance.

The Business Case for Using Hybrid Hosting
As was noted earlier, the benefits of a dedicated server are stability, security and regulatory compliance. The benefit of ISP hosted cloud servers is the ability to scale up and down quickly, and the utility pricing model, which reduce the need to plan for, and invest in, equipment to counter expected and unexpected loads.

A hybrid model uses dedicated servers for hosting mission critical applications (operations management, ERP, finance, customer relations management (CRM), sensitive data
(customer, marketing, financial or product order records) or regulated programs (client medical reporting, credit card processing). Cloud servers are used to host web servers, serve files, and respond to variable loads (content delivery, online sales during promotions, event ticket sales). In the case of dedicate/private cloud/public cloud hybrids, both type of clouds hold the same kind of application, and an integration manager balances the load between the clouds to maximize responsiveness and minimize cost.

The ideal hybrid has the security and stability of dedicated hosting, with the automated scaling of cloud hosting. It lowers fixed costs, because loads are handled through the cloud, rather than by stand-by dedicated hardware. Hybrid hosting allows to better match server use and processing load, and because cloud servers can be turned off when not needed, and payment is for used resources only, operating cost are lower.

Additional benefits to businesses include increased speed to market with streamlined development and rapid provisioning, maximal availability and uptime, instant scaling and unlimited storage, all without long term contracts or financial layouts. These reduce the complexity of contingency planning, and the associated mitigation cost.
The use of internal (private) clouds in addition to dedicated servers is another advantage of cloud technology. While private clouds do not have the cost and scaling flexibility advantages of external clouds, they do improve hardware utilization (in the in-house data center) through server virtualization. Servers replication lets administrator move virtual servers between physical servers, to maximize responsiveness and reduce waste. The use of internal clouds should eventually lead to higher adoption rate and to easier integration with external clouds.

Hybrid Hosting Scenarios
What is acceptable for a business often depends on size and existing IT infrastructure. Whereas a medium size business is likely to have an IT department, often have in-house data centers and may use a mainframe to process financial and other data, a small business may outsource its IT services and use online sales management, accounting, web and email hosting. Different, even conflicting, cloud use scenarios, can co-exist at different sides of the business universe.

Hybrid hosting components are used for their unique advantages. Here is a number of real- life hybrid hosting use cases, alongside recommended practices and applications of the technology.

•    Placing the production system on a dedicated server to maintain the security and stability of the running software, while keeping development and testing environment on a cloud to lower initial financial outlay on development servers and lower the cost of testing.
•    Have the database residing on a dedicated server, taking advantage of I/O exclusivity and all the power of the hardware, while a web front end is deployed on the cloud, and communicates with the database server for record keeping and processing. Security settings and policies can assure that data flow is unidirectional, from the web server to the database, and not the other way around. For example, in medical records or financial transactions cloud-hosted web servers can easily scale up as needed to collect user data and send it securely with encryption to the database on a dedicated server) User records and transactions data are secure in a compliant environment on the dedicated server.
•    Hybrid e-commerce hosting – the shopping cart software, database engine, product catalog, inventory and pricing databases are kept on a managed dedicated server. Multiple independent customer websites are each hosted on a virtual server in the cloud. This way each e-store owner can manage the look, security and performance of his/her site, or independently select additional services such as backups and automated scaling.
•    Using the cloud for data protection, backup, and disaster recovery: online applications are delivered from a dedicated server, while back up data is kept in the cloud. In a similar vein, data heavy applications can use a virtualization platform for backup and disaster recovery. Cloud storage is offered by Amazon, Microsoft, and many smaller providers, with pay-as-you-go charges and even a limited amount of free space.
•    Using the cloud for failover: keeping duplicate instances of an application on a private (dedicated or cloud) server and on a hosted external cloud, and using a cloud integration manager to direct requests to the public cloud if the internal infrastructure fails to handle the increased load. The private server or cloud uses a public cloud as an on-demand failover platform. A variant is using one public clouds as a production platform, and other public clouds as failover platforms.
•    Using the cloud for high availability: in a similar manner, keeping duplicate server instances on private and public clouds, and using a federated hybrid cloud manager to raise new servers or direct users to the less loaded components in order to improve responsiveness.
•    Data processing: the data and software for splitting the data sets, coordinating processing, sending raw data and receiving results is hosted on a dedicated cluster, while a public cloud service, such as Amazon’s Elastic Compute Cloud (EC2), is used for data crunching. Tools exist for using cloud servers for scientific computing, or Infrastructure as a Service, which deploy cloud servers to match the data analysis demand.
•    Segregating functionality: using a mix of dedicated servers, private and public cloud apps, to run a small business. For example, sale force management on one cloud, data storage on another cloud, Google apps (mail and document processing) on a private cloud, web servers on Microsoft or Amazon servers, and accounting, payroll and human resources software on dedicated servers.
•    Legacy systems and applications not suitable for multi-tenant environment on dedicated, other applications on the cloud.
•    Discretionary projects, product development, product testing, on the cloud, taking advantage of scaling and utility payment to reduce cost, while dedicated production systems are insulated on dedicated servers.

Hybrid Hosting Challenges and Direction
While many businesses are considering hybrid hosting, only a few are fully committed to it. The reasons? Complexity, security and performance concerns. Here are the challenges in more detail:

•    Security – the number one concern about cloud computing is data security and control, not in the least because cloud servers share the host hardware with other
users. Security policies may be modified to allow automated addition of new servers into the network. Careful planning and implementation is required to prevents penetration of the dedicated network through the cloud servers. To respond to these concerns, cloud providers offer virtual private clouds, including a private dedicated network and walled hardware for exclusive use by a single client. Security is ehnanced by firewall, encryption, private VPN access, and security settings such as configuring DMZ between cloud and dedicated/colocated servers.
•    Inter-cloud compatibility – code written for Microsoft Azure will not run on Amazon EC2 without modification, and vice versa. Clouds are not always compatible, even when they share an underlying technology. ‘…there is little in the way of inter- cloud communication to make the system efficient’ – from Vinton Cerf blog. Work on improving standards in the cloud continue, but the integration and communication between the components of hybrid hosting (dedicated and clouds), and especially between different clouds, remain a challenge. The success of hybrid hosting depends how seamlessly and efficiently it operates.
•    Legacy applications – different vendors provision different software stacks for developing and running applications, but most include only the latest tools and languages. Existing applications may have to be rewritten to take advantage of the clouds, quite a challenge for an organization. Even when the code is compatible with the cloud server stack, software may have to be modularized and rewritten to enable easy inclusion of virtualized environments. On the bright side, software is increasingly written as a service, so components that are hosted on a dedicated server can work alongside software in the cloud.
•    Maturity – the cloud component of hybrid hosting is relatively new and unproven. As time goes on, management tools, development tools, monitoring, integration will improve and coalesce around a set of standards. A track record of performance and stability is growing, and the increased use of private clouds allows easier integration with public clouds. ‘Configuration, provisioning and administration through a single web portal, any time, anywhere’ is becoming the norm in cloud management tools.

The Future of Hybrid Hosting
Private and public clouds, and the virtualization technologies that power them, are promoted forcefully by powerful vendors such as Microsoft, Google, Amazon, AT&T and many others. VMware and Citrix are aggressively pursuing the data center with virtualization products, while IBM, HP, Dell and other system integrators are developing enterprise systems. ISPs offer cloud based servers, storage and content distribution networks as part of their hosting product mix. Start-ups offer cloud management and integration tools, making it easy to create private clouds and operate seamlessly cross the boundaries between private and public clouds.

The emergence of virtualization tools for in-house use bodes well for the adoption of all cloud types. Once organizations feel comfortable with the deployment and use of internal clouds, software will be developed in them. The next step is hybrid hosting with similar internal and external clouds, followed by the use of multiple cloud services.

In other words, the forecast for the cloud is sunny. ISP’s should considering how to participate in cloud hosting and offer hybrid hosting solutions, and whether the time is ripe to commit to a given cloud technology, or work through multiple technology partners. Either way, it is important to have a blueprint for the future use of cloud and hybrid hosting models, because both are maturing quickly and will be a competitive advantage in the future.