Couchbase's Plasma storage subsystem for Global Secondary Indexes uses a memory quota to manage its resources efficiently by employing eviction algorithms to free unnecessary memory. The subsystem organizes data into variable-sized pages and monitors memory use, triggering "Burst Eviction" to offload pages to disk when memory exceeds the quota, which can negatively impact CPU usage, latency, and throughput. To mitigate these effects, "Periodic Eviction" runs at regular intervals to track active pages, ensuring that only non-essential pages are evicted, thus preserving memory headroom for potential spikes in usage. The eviction process, controlled by configuration parameters like the evictSweepInterval, is optimized by the swapper thread using the clock algorithm to identify pages for eviction. By adjusting parameters like cache_hit_ratio and resident_ratio, users can fine-tune the system's memory management to ensure optimal performance.