What do service levels really mean for Exchange Server? We hear the term thrown about in the industry, but have we looked at what service levels mean to our own Exchange deployments?
Service level agreements (SLAs) need to come from our business requirements, which means we must ask our customers tough questions that determine whether and how long they can live without Exchange service. How important are the applications running on Exchange to the business functions within the organization? If the customer can't live without Exchange, how much does it cost per minute, per hour, or per day to keep Exchange running? Only through business justification can we determine proper SLAs. This justification can also help validate how much money we want to spend striving toward those SLAs.
After we've worked with our customers to determine the importance of the Exchange deployment to them, we need to design SLAs that ensure that we meet their business needs. Exchange deployment SLAs come in many flavors, but they usually fall into one of four categories: performance, disaster recovery, security, or management.
Performance SLAs deal with message delivery and response time metrics. Delivery SLAs, such as maximum message delivery time, are the most common performance SLAs. Delivery SLAs typically take the form, "95 percent of messages will be delivered worldwide within 15 minutes." In some cases, the SLA also defines the other 5 percent (e.g., the remaining 5 percent will be delivered within 30 minutes).
Disaster recovery SLAs are also very important for Exchange. The important disaster recovery SLAs are those that deal with how long it takes to get our data back when something goes wrong. Disaster recovery SLAs can focus on the entire server or be more granular by providing guaranteed recovery times for an information store (IS), a mailbox, or even an individual item in a folder.
Security SLAs include metrics such as assurances about virus-detection rates or encryption. Management SLAs are established to meet user and account maintenance requirements.
SLAs are the only real means we have to ensure that our Exchange deployments deliver business value to our organizations. Without SLAs, providing consistent service is difficult, and management has no criteria on which to base staffing, procedures, training, and other key investments. I hope you haven't forgotten SLAs in your Exchange deployment. With the release of Exchange 2000 Server, make sure you have factored in your SLAs and the new flexibilities that Exchange 2000 offers your migrations plans.
