High Availability: An Introduction

High Availability: An Introduction

High Availability: An Introduction

In the world of IT and computing today, you may increasingly hear the word “high availability.” This term is generally used to describe the quality of a system, through the period of time that a service is available, including the time required by the system to respond to a request.

As the words denote; “high availability” of a system means being available almost always. Conversely, a system that never fails would mean it accomplishes complete, 100 percent availability. Typically, a high availability system guarantees 99 percent availability. For instance, in a period of one year, only 1 percent of downtime or 3.65 days is permissible.

Such downtime may either be periods of maintenance (whether scheduled or unscheduled), or outright system failure indicating lost productivity and recovery period. The latter is obviously what enterprises and other organizations seek to avoid, because it affects their bottomline. High availability software solutions address such downtime and service interruptions mostly through technologies such as database replication tools.

Creating a standby environment

Database replication is important when dealing with real-time information and steady streams of data, which is the norm these days in many industries. A standby environment is effectively created, so that data can be analyzed for real-time queries and reports without disrupting the original source.

Instead of copying information as is, techniques such as log-based capture are used so that updating of data is more responsive especially when dealing with an immense database. This approach reduces latency, or the delay between the moment that data is generated and the moment it is copied or transferred.

A standby environment is also important to prevent data loss in instances of failure by simply creating copies of the data for continuity of operations as well as for recovery purposes. By comparing primary and standby environments, errors can be effectively analyzed and prevented in the future. Any differences in data can also be repaired or rectified.

System threats and challenges

What instances should businesses and organizations watch out for in terms of data security and availability? A system outage can be caused by many factors, including network interruptions or bugs in the software, as well as external factors like power outages or natural calamities that lead to infrastructure damage. Human error is also a common source of downtime.

As such, these are the same components that need to be taken into consideration when aiming for high availability systems.


Highly available hardware such as servers should be resilient to power interruptions and outages. Common hardware such as hard drives and network interfaces should be highly reliable and stable as well.


The operating system and the application itself should be able to handle unexpected failure that could lead to system restart, for example.


Redundant servers are important in different data centers in various geographical locations. This spreads out the risk of damage and interruption in instances of fire, flooding, earthquake, and other disasters. Housing your servers all in one area or location puts your data at great risk of being wiped out in an adverse physical situation.


A redundant network strategy is also important in the event of possible failure during unforeseen network outages.

Investing in high availability systems

As with any major technological application, building a high availability system takes considerable resources in terms of time, money, and talent. However, given the risks of data loss during unforeseen outages and interruptions, you cannot afford not to plan well and take preventive measures. Investing in the right data replication solutions will pay off in the long run not only in terms of preserving your business, but also in terms of peace of mind.


Guy Galboiz is an Entrepreneur, Technology Enthusiast and Internet Marketing Expert. He loves sharing his knowledge and opinion on latest technology advancements.