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These metrics help diagnose I/O and memory performance in SQL Server.
Logical reads: The number of 8KB pages read from the buffer cache (memory). High logical reads can indicate inefficient queries or missing indexes.
Physical reads: Pages read from disk because they were not found in the buffer cache. Physical I/O is orders of magnitude slower than memory access.
Page Life Expectancy (PLE): An indicator of how long pages stay in the buffer cache before being evicted. A consistently low PLE suggests memory pressure or inefficient queries repeatedly flushing the cache.
Senior engineers use these metrics together to determine whether to focus on query tuning, indexing, or adding memory/storage capacity.