The good part of Cloud is high availability (HA). It should be hard to find downtime if you are using PaaS or SaaS. This is because HA is often considered in the architecture design. Thus, this is a great push factor for you to move to Cloud. Traditionally, on premise architecture must cater the required licences for HA. Will you move to Cloud for the sake of HA?
HA will be Norm
You may notice that Cloud applications are all HA as a norm. It is not surprising that you should either upgrade your on premise to HA or move to Cloud. The cost of HA is definitely much higher and not affordable in the past. It is usually done for large global enterprise. Most of the time, only production environment is HA because of the high cost of maintenance.
Time to HA on Cloud
If one of your objectives is HA, it is worth consider the cost savings for moving to Cloud. Many Cloud cost do not explicitly state how much HA will be in their cost. Thus, you need to compute the HA costs into your existing total cost of ownership before comparing to cloud cost. You will see that HA will one of the key justification on why you want to move to Cloud.
Building HA into your architecture used to be a costly ordeal. Now, many applications have been included HA as part of their product offerings. It is a ripe time for you to move to Cloud if HA is a critical component. The cost savings can be substantial because you can have HA across different types of development environment beside your production.
Danny Kwok 