Elasticsearch+OpenSearch Tuning。Shard Size 20-50GB Sweet Spot・Number of Shards計算 (Total Data÷40GB)・Replica 1+ (HA)・refresh_interval 30s (Indexing高速化)・index.translog.durability async・index.codec best_compression・bulk API 5-15MB・Hot-Warm-Cold Architecture (ILM Index Lifecycle)・Frozen Tier (Searchable Snapshot)・Cross-Cluster Replication CCR・Cross-Cluster Search CCS・¥0 OSS-¥¥¥¥¥¥/月、2026年Elasticsearch 9 Apache 2.0復活影響Migration拡大。