Tair ESSD-based instances are developed based on enhanced SSDs (ESSDs) and are compatible with core data structures and APIs of open source Redis. These instances can provide large-capacity, low-cost, and persistent database services. Compared with open source Redis, ESSD-based instances reduce costs and improve data reliability. In addition, ESSD-based instances reduce the amount of reserved memory that is required for the forks of native Redis databases. ESSD-based instances are suitable for scenarios that store warm and cold data, and require compatibility with open source Redis, large capacity, and high access performance.
Native Redis uses volatile memory as storage media. This causes the following issues when business continuously grows and data volume rapidly increases:
- Latency and jitter occur when Redis processes a large amount of data.
- When data accumulates along with the development of business and the access volume decreases, the actual performance is higher than required.
To resolve the preceding issues, Alibaba Cloud released ESSD-based instances that use ESSDs as the storage media. ESSD-based instances are cost-effective and reduce up to 85% costs compared with ApsaraDB for Redis Community Edition instances. A storage-optimized instance can provide a storage capacity that reaches hundreds of terabytes and higher data reliability. For more information, see ESSDs. Compared with open source Redis, ESSD-based instances reduce costs and improve data reliability. In addition, ESSD-based instances reduce the amount of reserved memory that is required for the forks of native Redis databases.
|Comparison item||ESSD-based instance||Hybrid-storage instances (phased out)||Open source Pika|
|Compatibility||Compatible with most of the open source Redis commands.||Delivers compatibility with all commands of native Redis databases.||Uses commands quite different from those of native Redis databases.|
|Data persistence||Supports half synchronization and asynchronous synchronization.||Synchronizes data in an asynchronous manner.||Synchronizes data in an asynchronous manner.|
|Data distribution||Stores data only in disks by using the Alibaba Cloud TairDB storage engine.||Stores the keys and values of hot data in the memory and all keys and values in disks.||Stores data only in disks by using the RocksDB storage engine.|
|Performance||Delivers a performance that is 60% of the performance of native Redis databases. The performance of ESSD-based instances for complicated data structures, such as list, hash, set, and ZSET, is 10% higher than the performance of open source Pika.||Delivers the same performance as native Redis databases for hot data in the memory. The performance for cold data is not guaranteed. The overall performance of a hybrid-storage instance depends on the distribution of cold and hot data.||Delivers a performance that is 60% of the performance of native Redis databases.|
|Scenario||Warm data||Data that is randomly accessed.||Warm data|
|Cost||Reduces up to 85% of costs compared with ApsaraDB for Redis Community Edition instances.||Requires 20% higher costs than ESSD-based instances on average.||Requires lower costs for on-premises physical devices but higher O&M costs.|
- Q: What Redis version do ESSD-based instances run?
A: ESSD-based instances use an engine that is developed by Alibaba Cloud. This engine is compatible with Redis 4.0. For more information about the support for commands, see Limits on commands supported by ApsaraDB for Redis Enhanced Edition (Tair).Note To support specific components or clients that are needed to detect the engine version, such as Redis-shake, ESSD-based instances retain the redis_version parameter in the response of the INFO command. The value of the redis_version parameter is 4.9.9.