By Michael Bilancieri

Recent reports show that the average employee checks email once every 15 minutes, with power users checking email up to 40 times per hour. Combine this with the growing use of personal mobile devices and it is easy to see that employees are attached to their email at all times, with some checking their device in real time as each email arrives. With minimal tolerance for downtime, employees expect access to their email 24x7, seeing it as a critical business communications tool.

IT administrators are constantly challenged with meeting the “always on” expectations of employees. Increasingly strict service-level agreements (SLAs) and demanding users require non-stop access to email and other collaborative features of Microsoft Exchange. Availability of Exchange is vital, as well as protecting the integrity of Exchange data. Each component of the Exchange infrastructure must be individually considered in order to maintain optimal availability levels. Even if you protect your mailbox server to the highest degree, the Exchange server may not be accessible if the DNS server fails.

To help your company protect its Exchange environment, there are some sound steps for achieving optimal availability. The tips will to help identify what availability levels should be designated in order to achieve Exchange SLA commitments with fewer resources and lower costs.

Determining Availability Objectives

Creating goals for your availability program is an important first step in formulating Exchange protection strategies. This is typically done by establishing Recovery Time Objectives (RTO), the time it takes for an application to be up and running again, and Recovery Point Objective (RPO), the point in time to which an IT professional can recover data in case of a failure.

Baselines for the SLAs you commit to for the overall company, business units, or specific are established by the RTO and RPO that you initially set. There may be different Exchange SLAs for different users within your company. For example, the majority of a company may be able to withstand Exchange downtime for up to one hour but an executive group could require 24x7 email access. In addition, consideration should be given to what level of protection is needed for the other components of your Exchange infrastructure, such as Active Directory and DNS servers.

Identifying Availability Levels

There are various levels of availability to consider for different applications and their support infrastructures, starting with basic failover and recovery, moving up to high availability, and all the way to system level fault tolerance for extremely transaction-sensitive applications.

1. Recovery: The recovery level is for those applications for which some downtime is tolerable (often up to a day or more). Some downtime is perfectly acceptable, and even significant downtime won’t have a detrimental effect on the business. Assurances that recovery will happen is not a requirement.

2. High Availability: This level is best suited for the majority of applications that run the business, such as email, CRM, financial systems, and databases. These systems have high downtime costs, and therefore short RTO  requirements. These applications require assurances that they will not be down for extended periods should failures occur.

3. Continuous Availability:This is the highest level of availability during which even brief moments of downtime or a single lost transaction can be extremely detrimental and/or costly to the client or business.

As you establish availability objectives for the different groups of Exchange users, it is important to consider the protection requirements for your entire Exchange infrastructure, beyond just the mailbox server. It is necessary to protect all of the components of the Exchange environment, in addition to the different workloads deployed on the server. Also, the way you use Exchange today may not change in the future and need to be adjusted to meet new requirements. You may use Exchange today for general correspondence, but within the next year you may plan to use email to process orders. This increases the importance of having multiple levels of availability to assign to the components of the Exchange infrastructure and Exchange user groups. Flexibility will be key when changing those levels as your business evolves.

Assigning Appropriate Availability Levels in Exchange Environments

A meaningful exercise to undertake is to apply various levels of protection to your Exchange infrastructure based on your SLA commitments. First take a look at the users and their requirements for Exchange access. Do you have multiple user groups with different SLAs or do you have a single SLA in place for all users? If you have a single SLA in place company-wide, you can deploy those users in workloads based on email usage and assign them the appropriate level of protection. However if you have different SLAs for different business groups, you can divide those into multiple workgroups on the mailbox server based on their SLA requirements.

As in the case mentioned above, if an executive group needs a 24x7 uptime, those executives should be consolidated in a dedicated Exchange workload and assign a level of protection that will provide continuous availability. Sales people often join executives in this category, requiring non-stop access to email and Exchange collaboration features. Other employees may have less stringent SLAs in place and would require a lower level of protection.

It is also important to keep the components of Exchange, including the DHCP server, DNS server and Active Directory server, up and running. If one or more of these components goes down, requiring the IT administrator to manually intervene could cause excessive downtime for Exchange. Automatic recovery from failures makes it possible to keep the Exchange environment operating to meet SLA commitments. Assigning a level of protection to the supporting systems, including  the DNS, DHCP, and Active Directory servers, equivalent to that necessary to meet Exchange SLAs is as important as protecting the actual Exchange servers. Any single point of failure could bring down a seemingly well protected Exchange server.

A company may also have a BlackBerry Enterprise Server (BES) and/or Client Access Server (CAS) implementation for remote workers to serve as a secondary or backup method for remote email access. The BES and CAS implementations should be protected to the level you require based on your remote email access strategy and user SLAs.

Establishing RTO and RPO for SLA commitments, determining the right level of availability protection to meet these commitments, and protecting all components necessary to support an Exchange environment will help create a robust and reliable messaging system.

Michael Bilancieri is the Senior Director of Products at Marathon Technologies