Couchbase Server offers two storage options for global secondary indexes: standard GSI and memory optimized GSI (MOI), with MOI introduced in version 4.5 to address the challenges of high-demand applications like travel-itinerary and fraud detection. MOI provides significantly better latency and throughput compared to standard GSI by utilizing lock-free processing and skiplist structures for in-memory storage, avoiding the slower disk speeds of standard GSI which uses ForestDB. MOI requires machines with large memory capacity since it keeps indexes in RAM, while standard GSI can spill over to disk, thus relying heavily on IO subsystem performance. The creation process for both types uses the CREATE INDEX command, but MOI offers additional statistics and alerts to aid in index placement and management. These statistics help administrators monitor memory usage, ensuring that indexes are placed where sufficient memory is available, and alerts notify them when RAM usage approaches critical levels. Future discussions will cover enhancements like the Circular Write Mode for standard global indexes.