Virtualizing MongoDB on Amazon EC2 and GCE: Part 2` discusses best practices for virtualizing MongoDB in public clouds, specifically Amazon EC2 and Google Compute Engine. To perform well, databases require RAM and low IO latency, which can be achieved by using high-performance instance types, provisioned IOPS, and optimized storage configurations. For EC2, using EBS-optimized instances with provisioned IOPS is crucial for predictable latency on IO operations. In contrast, GCE's Persistent Disks are implemented as stripes across many physical disks, making RAIDing redundant and volume size directly correlated to available IOPS. The article emphasizes the importance of following specific guidelines for each cloud provider to ensure optimal performance and reliability.