A ‘Service Level Agreement’, commonly referred to by its acronym SLA, is an understanding of service between two parties and is specific to the level or scope of service that will be provided. It will specify state what kind of guarantees or warranties the service provider shall provide these services under and what actions can or will be taken if the services provided fall underneath the specified scope.
SLAs and Web Hosting
In the the Web world, an SLA is a common term when talking about Web hosting. Though SLAs can get very complex the simplest model in regards to Web hosting typically states a refund of monthly fees will be provided if any downtime should be experienced. So for example if the SLA states the hosting provider will provide 99.99 percent up time and there is an outage lasting longer than approximately 4.3 minutes in a 30 day period, the provider would then refund some of the customer’s money.
Understanding an SLA
It’s important that you understand your SLA and understand exactly what it means. Many vendors provide their customers an SLA as a guarantee, a way to make them feel better during the purchasing decision – i.e. it’s a marketing tool. However it’s typically not as simple as ‘if your site goes down, we give your money back’. Typical hosting SLAs compensate the customer an amount equal the value of time their service was not provided (outage). An example:
Host Guarantee: 99.99% Uptime (no more than 4.3 minutes of down time in 30 days)
Actual Outage: 60 minutes
Time Outside SLA: 57.3 minutes
You Hosting Fee: $20/month
Refund provided by SLA: $0.03 (rounded up)
You can see that down time is quickly going surpass what is reasonable for your business long before the SLA provides you any real financial satisfaction. I often advise my clients that SLAs are certainly something you want to research and understand when you are hosting some real infrastructure, otherwise for for small infrastructure or shared plans, it’s just not going to matter from a business perspective.
Not All, In Fact Most, Outages Wont Even be Covered by a Typical Web Hosting SLA
When it comes to hosting, an SLA will typically cover connectivity and not your specific site/application performance. So basically it means that the hosting company’s connection(s) to the internet has to be up and running and that the network your hosting infrastructure is on is up and running (or at least as much as they guarantee). Notice I said nothing about the performance of your Website. If your Website’s performance should drop and or the site even come offline, unless it is a DIRECT result of the host’s network connectivity (not your code, not the server or any other reason), then it probably is not covered by the SLA.