HA/DR – Insurance For Your Server. What it is And How To Achieve It.

The availability of the services that you provide is the foundation for the successful development of your business. If you are using the services of a hosting provider, it’s important thing to have some kind of guarantee that they will be able to provide the uninterrupted operation of your services. In this case, you should know that such guarantees are standardized and included in each service level agreement. They include such points as High Availability (HA) and Disaster Recovery (DR). What are those concepts, what benefits do they give you, and what do you have to keep in mind when looking for Dedicated Servers UK – that’s what we are going to look at in today’s article.

Service Level Agreement – what you need to know

The Service Level Agreement or SLA is an agreement that you make with your service provider to make sure that all the necessary conditions are met. In the SLA the rights and duties of both parties are specified, as well as the penalties for not following the guidelines of cooperation. Two of the important concepts that are involved in the SLA are Recovery Time Objectives (RTO) and Recovery Point Objectives (RPO). The RTO regulates, how soon the operation must be recovered in case of failure. The RPO in turn is a measure of the time between the last data backup and the point of failure. It determines how much data can be lost before it becomes a problem for the organization. Generally speaking, it depends on the frequency of backups and is expressed in units of time. An RPO of 3 hours means that backups must be made not less often than every 3 hours. An RPO of a week guarantees that the last backups will be made not earlier than a week ago, and so on.

With these metrics, the overall guarantee of uptime offered by the hosting provider may be estimated. It’s important to keep in mind, that better guarantees cost more – a 99,99% guarantee will be more expensive than a 99,9% guarantee. If you want to find the most cost-efficient solution, you need to calculate and compare, whether the costs of downtime are more than the costs of additional insurance.

As soon as these calculations are ready, you can make up your mind on which particular kind of server insurance is the most suitable for your business.

High Availability (HA)

High availability is a type of uptime guarantee which suggests 99,99% of uptime which is just 52m 9.8s of downtime a year. 

There are a number of software and hardware-based solutions that make this level of uptime possible, which include redundant servers, load balancers, and failover systems. On the one hand, these technologies are constantly monitoring your system on the subject of any failures occurring. On the other hand, they make sure to implement the necessary measures in the eventual event of failure, redirecting your traffic and backing up business-critical applications with secondary servers to bring the possible downtime to a minimum.

One way of providing High Availability is by involving cluster-based solutions. These solutions consist in using two servers that are working together to back up one another in the event of failure. The cluster-based solutions are divided into two models: active-active and passive-active.

The active-active model suggests that two servers are working simultaneously, sharing the workload in half and being able to back up one another if something.

Passie-active model, on the other hand, suggests the constant operation of one server with the secondary server in standby mode, reserver only in cases where the backup is needed.

Both solutions cope well with providing the highest amount of uptime but have certain differences and usage specifications.

The active-active model can give you potentially a better level of performance, reaching even the 99,999% of guaranteed uptime, being in a way more flexible and scalable, but it’s more complex in terms of maintenance and configuration, which makes it also more expensive.

Passive-active model is not as “perfect” as the active-active solution in terms of potential performance, but it’s on the contrary easier to set up and maintain, hence cheaper, while giving you de facto an almost equal quality of service.

Disaster recovery (DR)

Disaster recovery is a part of server insurance that covers various measures that ensure that the operation of your server is restored as soon as possible in the event of failure. Available disaster recovery options include:

  • Backup and recovery: creating copies of your data and storing them at a different data center to exclude data loss even under the most dramatic circumstances.
  • Business continuity planning: creating a plan B of is some critical parts of business infrastructure that refuse to operate.
  • Cloud disaster recovery: using cloud services as additional reliable storage to provide the safety of the most precious data.

When looking for a hoster, make sure that the necessary disaster recovery options are included in their service level agreement.


As you have seen, there are various ways of how the uninterrupted operation of your server can be provided. Good providers usually offer various options to choose from, so when looking for a hosting plan, figure out what kind of insurance your business needs, how critical maximum uptime is, and how much you are ready to invest in it. Then, study carefully the solutions offered by various providers and make sure they are offering exactly the insurance plans that fit your business. In this way, you can achieve the optimal uptime of your server with the most cost-efficient solution available. 

About alastair walker 11398 Articles
20 years experience as a journalist and magazine editor. I'm your contact for press releases, events, news and commercial opportunities at Insurance-Edge.Net

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