Case study

Highly available messaging

Implementing a reliable solution at a readily available cost

With email forming the backbone of modern business communications, it has quickly become a mission critical service. HMY Radford rely heavily on their email systems for business communication, receiving orders, and collecting information from engineers in the field.

After their underlying storage platform developed a fault, Radford’s Exchange 2010 email databases became corrupted. This resulted in an email service outage while the data was recovered.

Following recovery of their systems, Radford engaged Waterstons to improve the resiliency of their email service, so that a fault in the future would not disrupt business operations.

Radford were keen to employ a solution which spanned both physical and virtual hardware, so that they were not fully dependant on either platform. At the same time, they wished to keep capital expenditure to a minimum in order to prevent a significant dent in their IT budget.


Waterstons determined that a traditional server clustering solution utilising expensive shared storage was too costly, and did not provide adequate protection against a similar storage fault in the future. A solution based on Microsoft Exchange Database Availability Groups (DAG) was selected to provide maximum resiliency.

A typical highly available DAG installation on Exchange 2010 requires a minimum of 4 Exchange servers – quadrupling the hardware and server licensing requirements for Radford’s Exchange environment in order to implement high availability.

Waterstons chose to offload the responsibility of directing clients to appropriate servers to a pair of KEMP LoadMaster network load balancer devices. In doing so, Waterstons were able to consolidate the remaining Exchange services onto just 2 servers – 1 virtual and 1 physical. Instead of 3 new servers, Radford now only had 1 new server to procure and license.

As a bonus, the KEMP LoadMaster devices may also be used to provide high availability services to other systems at HMY Radford, should the need arise.

The Benefits

In the event of a future Exchange server or storage failure, Radford’s email services will be automatically transferred to the second server, and normal service will continue.

In addition, HMY Radford are now able to reduce their risk exposure by keeping their email infrastructure updated against new security vulnerabilities as they are discovered, by installing critical patches during the working day.

Previously, such an operation would have necessitated a system outage, but now Radford are able to take individual servers offline for maintenance, without affecting the continuity of their email services.

More Information

Microsoft Exchange
Microsoft Exchange is the industry leading messaging platform; incorporating email, calendaring, contact management, task management, resource booking, and voicemail technologies; and when integrated with services such as instant messaging (Lync), telephony, and SharePoint provides Enterprise collaboration and document management.

Radford are part of a larger group of companies who implement a common Exchange 2010 messaging system which spans multiple continents. Although other companies have their own highly available configurations, Radford’s single Exchange server was a single point of failure for UK services.

Database Availability Groups Database
Availability groups (DAG) are a high availability technology that can be deployed as part of a Microsoft Exchange 2010 or 2013 infrastructure. They replicate data between two or more Exchange servers so that no matter what happens to one server or set of storage, you’ve always got an up-to-date copy elsewhere that can immediately take over to keep your business running.

Traditional methods of clustering Windows services work by sharing a single set of storage between multiple servers. Although this protects you against a server failing, you are completely reliant on that single set of storage. If something happens to your data then all of your clustered servers are unusable.

DAGs improve on this by replicating data to multiple locations. They only replicate valid data transactions, so if something accidentally corrupts or deletes your data on one server the others are fine.

Load Balancing
Replicating your data is great, but it’s only useful if you can access it. Network Load Balancing (NLB) technologies are used to spread network traffic between functioning servers and automatically route traffic to alternative servers if one fails.

In very large deployments, dedicated load balancer devices are common. These devices are designed to handle multiple millions of simultaneous connections, and typically have a price tag to match. On the lower end of the scale the inbuilt Windows NLB is common for deployments consisting of a few servers.

The obvious advantage of Windows NLB is that if you’ve got a Windows server it’s effectively free. The disadvantages are that it’s not very clever, and it can’t share a server with a DAG. For a small but highly available Exchange deployment the typical solution is to have at least 2 servers to handle the load balancing, and at least 2 more servers to form the DAG, making a minimum of 4 Exchange servers. That means 4 servers to license, but more importantly if you’re deploying on physical hardware that means 4 servers to purchase, accommodate, and maintain.

KEMP LoadMasters
Waterstons chose to deploy KEMP LoadMaster devices to handle the network load balancing at Radford. KEMP offer a range of load balancers which address the high availability needs of Exchange at a cost that doesn’t preclude smaller deployments. By using KEMP LoadMaster devices, Waterstons were able to minimise the overall cost of the highly available Exchange deployment, whilst taking advantage of advanced health checking capabilities that you don’t get with Windows NLB.

A Gold Standard
Both Waterstons and KEMP technologies have been awarded the Microsoft Messaging Gold Competency, which demonstrates best in-class capability with Microsoft Exchange solutions. The LoadMaster range of devices are designed specifically with Microsoft Exchange workloads in mind.

Combining class-leading KLEMP hardware with Waterstons' experience of designing cost-effective and resilient solutions provided HMY Radford with an always on messaging service that didn't break the bank.

More importantly for us, we also needed a Business Partner we could trust for project delivery and that Partner is Waterstons. I am convinced that their IT expertise has made a major contribution to our system’s continued uptime and I highly recommend them
Mark McDonald IT Manager, HMY Radford