You must purchase different specifications of ApsaraDB for Memcache instances based on your business needs. For detailed specifications of ApsaraDB for Memcache instances, see Instance specifications.
After a specification is determined, the following three limits are applied to the instance:
Memory capacity limit: the limit on the total capacity of KV pairs that can be stored by ApsaraDB for Memcache. When this limit is exceeded, ApsaraDB for Memcache clears existing data according to the FIFO policy. Therefore, some data may disappear before the expiration time.
Throughput limit: the limit on the throughput for an instance specification. For more information, see the following figure. This limit mainly applies to the traffic. You can view whether the output traffic of this instance exceeds the limit at 23:00. If yes, the following error appears: status code: 133, message: OCS flow control.
QPS limit: see the following figure for more information. This limit mainly applies to concurrency.
You can view the preceding limits in Resource Monitoring on the console.