All information is extracted from http://azure.microsoft.com/en-us/support/legal/sla/
Web sites SLA is 99.9%, calculated over a monthly billing cycle. That means a web site should not be available in a month for at most 43.8 minutes.
Important note for web sites: to be covered by SLA, the web site must be deployed at least in the Basic web hosting plan mode.
Traffic Manager SLA is 99.99%, calculated over a monthly billing cycle. That means during one month the traffic manager system may not respond for at most 4.32 minutes.
SQL Database SLA is 99.9%, calculated over a monthly billing cycle (maximum downtime 44 minutes).
Cloud Services when deployed with at least two role instances in different fault and upgrade domains, the Internet facing roles will have external connectivity at least 99.95% of the time.
When deploying a web site, use a “web role” instead of a “web site”.
Implement retry logic in the code accessing an SQL Azure database (for example, Entity Framework 6 has this logic built-in, see http://msdn.microsoft.com/en-us/data/dn456835.aspx).