An Introduction to “High Availability”


With an increased demand for reliable IT network infrastructures, the term High Availability (or HA) is becoming very popular.

Why is HA Important?

A 13 minute network outage for Amazon in June 2008 cost them close to $31,000 per minute, based on the previous quarter’s global revenue of $4.13 billion. Based on current figures, unexpected downtime would cost the company over $200,000 every minute!
So while the need for HA is clear for large companies, it also needs to be affordable for smaller businesses.

What is HA?

While most modern servers have redundant power supplies and RAID arrays to help increase up time, there are many single points of failure that sometimes get missed.

One of the goals of high availability is to eliminate single points of failure in your infrastructure. A single point of failure is a component that would cause a service interruption if it became unavailable.

For example, if your servers are connected to an Ethernet switch, the server may be replicated and not considered a single point of failure, but if the Ethernet switch fails, your PC’s have no way of connecting to the server, in this scenario, the Ethernet switch is a single point of failure.

A number of our clients operate 24/7 or outside of normal working hours. These businesses understand that prevention is better than cure and as a result we’re increasingly being asked to design network infrastructure with no single point of failure.
This includes having multiple Firewalls/Routers configured as HA with multiple methods of accessing the internet, such as a leased line with FTTC backup or dual controller SAN arrays with multiple Hyper-visors in order to provide live migration of virtual servers which in turn are connected to multiple switches that are configured as a stack.

Below is an example of a High Availability Server setup with each component have multiple data paths.

Of course, true HA goes much further than that just the servers, any single point of failure needs to be considered, such as power or even geographical locations.

High availability architecture also goes hand in hand with backup and disaster recovery but the focus is on the original network design and investment early on. This is where long-term planning really pays off.

How can we help?

If downtime is a concern for your business or you would like to find out more then contact us and one of our specialists will be in touch.

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