The first consideration when deciding to move to a cloud-based model should be data classification, because it helps the organization to identify the sensitivity, value, and criticality of the data that will be stored, processed, or transmitted in the cloud. Data classification can help the organization to determine the appropriate level of protection, encryption, and access control for the data, and to comply with the relevant legal, regulatory, and contractual requirements. Data classification can also help the organization to evaluate the suitability, compatibility, and trustworthiness of the cloud service provider and the cloud service model, and to negotiate the terms and conditions of the cloud service contract.
Storage in a shared environment, availability of the data, and physical location of the data are all important considerations when deciding to move to a cloud-based model, but they are not the first consideration. Storage in a shared environment can affect the security, privacy, and integrity of the data, as the data may be co- located with other customers' data, and may be subject to unauthorized access, modification, or deletion.
Availability of the data can affect the reliability, performance, and continuity of the data, as the data may be inaccessible, corrupted, or lost due to network failures, service outages, or disasters. Physical location of the data can affect the compliance, sovereignty, and jurisdiction of the data, as the data may be stored or transferred across different countries or regions, and may be subject to different laws, regulations, or policies.
However, these considerations depend on the data classification, as different types of data may have different levels of risk, impact, and expectation in the cloud environment. References = ISACA, CISM Review Manual, 16th Edition, 2020, pages 95-96, 99-100, 103-104, 107-108.
ISACA, CISM Review Questions, Answers & Explanations Database, 12th Edition, 2020, question ID 1031.