Sysco is one of the world's largest corporations involved with food distribution. In this time sensitive industry, IT systems that are reliable and timely with good data and excellent responsiveness are critical.
There is no tolerance for downtime. Cloud systems offer up parallel systems so if a system goes down, action shifts seamlessly to the other systems. There is lots of scalability so the company doesn't get caught in lack of resource.
For these and other reasons, Sysco decided to move their systems to Amazon Web Services (AWS), one of the world's foremost cloud services. Sysco was in the midst of large ERP installations and upgrades, which are major, very expensive projects with the potential for downtime, particularly when the new services go live.
Sysco opted for a "strangler" technique of implementation, which involves identifying particular sets of functionality in the legacy systems and their ERP, rewriting them as modules so as to work in the new chosen systems and then implementing them on AWS. Eventually, the old systems can be shut down.
In recent years, they have been employing this method with considerable success. Costs are reasonable, and functionality is preserved and improved.
For a summary of this experience, check out this website.