Welcome to the third installment of “the five dangers of virtual servers”. In my previous post, I talked about the danger of interference from other customers’ VMs on badly-configured platforms. So let’s move on to the next potential pitfall:
Danger Three: The danger of not having a Service Level Agreement (SLA)
It’s one thing to say that a service is reliable, but quite another to put a money-back guarantee or Service Level Agreement (SLA) on it. Obviously what you want is a working service, not a money-back guarantee, but it certainly puts an emphasis on the provider having a standard to work towards.
Many providers say SLAs are a waste of time, and marketing hype. If they truly believed this, surely they’d offer an SLA anyway as they have nothing to lose?
Some virtual server products come without an SLA; some even charge you extra for an SLA. In short, any decent high-availability virtual server offering should have an SLA on both the network connectivity, but more importantly the availability of the “virtual hardware” of your virtual server.
A decent SLA should provide a realistic and achievable service level (100% SLAs are usually vanity only, or exclude so much that they’re almost pointless) and a penalty for the host if the SLA is not achieved. It should also be clear what the SLA covers. For example, a lot of network/connectivity SLAs cover only the provider’s own network in their data centre, and not their upstream providers. That means your server may be inaccessible but if it was due to their provider and not their own internal network, you’re not covered.
Our own UltraVM™ Cloud Servers come with a 99.95% ‘hardware’ uptime and network guarantee, although in reality 100% uptime is both our goal and what we achieve.
Daniel Keighron-Foster, Managing Director



