As much as companies like to customize SLAs to their particular needs, and hold IT providers accountable for meeting these stringent requirements, public clouds just don't operate that way. In an article
by Beth Stackpole, 3 truths about cloud software SLAs are outlined:
1. A one-size-fits-all SLA is common - vendors can't achieve the economies of scale promised by cloud if they have to provide different levels of service to different customers.
2. Expect relatively immature SLA terms - the cloud software market is still fairly immature, and contract terms are still evolving. They are often not as specific as you would want.
3. Multiple layers mean limited accountability - with networks that are NOT dedicated to a particular client, there really can't be strong guarantees about full availability. The internet and overall network infrastructure are beyond the purview of the cloud software provider, so concrete guarantees about availability and uptime are impossible to offer. If the network fails between you and the provider, there is no one to blame, no one is responsible.
All that being said, cloud software vendors generally maintain high performance standards, and customers enjoy good service at reduced costs.