Multi-cloud refers to the practice of using multiple cloud providers to host different aspects of an organization's infrastructure and applications. However, managing and orchestrating resources across various cloud platforms can be complex and challenging. This is where OpenStack, an open-source cloud computing platform, plays a crucial role in simplifying the management of multi-cloud environments.

Cloud migration involves moving data, applications, and processes from on-premises infrastructure to cloud-based platforms. This transition holds the promise of improved operational efficiency, enhanced security, and the ability to innovate at a faster pace.

DevSecOps is an extension of DevOps that emphasizes security from the outset. It's not about bolting security onto the end of the development process but rather integrating it seamlessly throughout the entire software development lifecycle (SDLC). By doing so, organizations can identify and address security vulnerabilities early, reducing the risk of costly breaches and ensuring compliance with regulations.

It's essential to acknowledge and address its weaknesses. Thorough planning, careful vendor selection, ongoing monitoring, and the implementation of complementary technologies can help organizations maximize the benefits of HCI while mitigating potential pitfalls.

Strategic cloud infrastructure planning is not just a buzzword; it's a necessity for modern businesses. It aligns IT with business objectives, optimizes costs, enhances scalability, fortifies security, and accelerates innovation. Moreover, it ensures that businesses can adapt to ever-changing market conditions and remain agile in a rapidly evolving digital landscape.