In amongst the SLA’s from your SaaS provider, guaranteeing you 99.99
% availability hides a dirty little secret. You’re going to receive service from them over a public network i.e. a network that neither you nor they control.
Strangely, outage is not the biggest problem as you can mitigate against this with failover and alternative network routing, but poor performance will surely kill the value of the app completely.
What happens when an app goes slow?
The management view: Users work more slowly. Actuality: beyond a certain slowness users stop using the app and revert to other techniques, i.e. local word docs and spread sheets etc. From a corporate point of view that’s a horrendous result.
We love SaaS apps , like Salesforce.com, online accounting: Quick Books or Sage etc, google apps, webex, etc. Part of the appeal is having no server infrastructure and no maintenance as well as a simple payment model. But, they are not hosted in your datacentre and indeed not even in the same datacentre as each other, so you are reduced to using a public network (the internet) to access them.
Now, this, as we know is highly variable in performance and we have absolutely no control over that perfrormance. Also, during our trial of a proposed SaaS application we would have had a limited number of users and the network may well have been performing fantastically - that’s no guarantee at all that that will be true when in production.
What we really need to know is, that aside from their SLA,the SaaS vendors have tested the application with low bandwidth availability, high loss and latency; factors all too common in the real world. Have you seen any information on these? You should have. You need it! Because in planning your public network connection you want to make sure you have plenty of capacity to run these mission critical applications, as well as the dross that is being run alongside them.
In fact you should consider strongly implementing quality of service and bandwidth management to prioritise these applications at your network boundary. When a tiered internet arrives, as it surely will, you’ll also want to subscribe to the higher level service for your SaaS apps, leaving Facebook and the like on a lower level service.
So the SaaS experience is only as good as the network. The SLA from your SaaS provider has no bearing on the network and the ISPs gives you no guarantees of internet performance, and so, fundamentally, there is no end-to-end SLA guaranteeing decent performance.
Beware and make provision with your own traffic prioritisation, load balancing and failover because bad performance kills all benefits of these apps, and you’ll wish you’d never gone there.
Posted by Frank Puranik
Frank is Product Director at iTrinegy. With more than 30 years in the computing industry. He is an expert in the performance issues of applications across the world’s most complex networks.