RDS的三个指标Free Memory、Active Memory和Freeable Memory之间有什么关系？
What is the relationship between three metrics of RDS: Free Memory,Active Memory and Freeable Memory?
AWS RDS的三个指标是什么：Free Memory（增强监控）、Active Memory（增强监控）和Freeable Memory（CloudWatch监控）？
它们之间有什么关系？
看看这两张照片。
三个指标的值不同。
让我分两部分回答你的问题。
- 增强监控和Cloudwatch监控有什么区别？
Amazon RDS Enhanced Monitoring — Look at metrics in real time for the
operating system.
Amazon CloudWatch Metrics – Amazon RDS automatically sends metrics to
CloudWatch every minute for each active database. You are not charged
additionally for Amazon RDS metrics in CloudWatch.
意思是，增强监控允许您监控操作系统计数器，而 cloudwatch 监控允许您监控性能计数器每个数据库实例。
- Free/Active/Freeable内存代表什么？
Enhanced monitoring info source
可用内存
The amount of unassigned memory, in kilobytes.
活动内存
The amount of assigned memory, in kilobytes.
可用内存
Official Source
The amount of available random access memory.
Units: Bytes
Freeable memory is not a indication of the actual free memory
available. It is the memory that is currently in use that can be freed
and used for other uses; it's is a combination of buffers and cache in
use on the database instance.
AWS RDS的三个指标是什么：Free Memory（增强监控）、Active Memory（增强监控）和Freeable Memory（CloudWatch监控）？
它们之间有什么关系？
看看这两张照片。
三个指标的值不同。
让我分两部分回答你的问题。
- 增强监控和Cloudwatch监控有什么区别？
Amazon RDS Enhanced Monitoring — Look at metrics in real time for the operating system.
Amazon CloudWatch Metrics – Amazon RDS automatically sends metrics to CloudWatch every minute for each active database. You are not charged additionally for Amazon RDS metrics in CloudWatch.
意思是，增强监控允许您监控操作系统计数器，而 cloudwatch 监控允许您监控性能计数器每个数据库实例。
- Free/Active/Freeable内存代表什么？
Enhanced monitoring info source
可用内存
The amount of unassigned memory, in kilobytes.
活动内存
The amount of assigned memory, in kilobytes.
可用内存 Official Source
The amount of available random access memory.
Units: Bytes
Freeable memory is not a indication of the actual free memory available. It is the memory that is currently in use that can be freed and used for other uses; it's is a combination of buffers and cache in use on the database instance.