My RDS instance class is db.m3.xlarge, its total memory is 15G, I used RDS for a while, RDS Freeable Memory continues to decline, currently less than 3G.
So Freeable Memory < total memory * 20%
This Picture1 (Freeable Memory) show this:
The Picture2 (Swap Usage) show this:
According to the link: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_BestPractices.html#CHAP_BestPractices.Performance.RAM
Memory
Freeable Memory – How much RAM is available on the DB instance, in megabytes. The red line in the Monitoring tab metrics is marked at 75% for CPU, Memory and Storage Metrics. If instance memory consumption frequently crosses that line, then this indicates that you should check your workload or upgrade your instance.
swap Usage – How much swap space is used by the DB instance, in megabytes.
According to the above paragraph, should I increase the instance to increase the memory? (Modify RDS instance from db.m3.xlarge to db.m3.2xlarge)
I also found this link:
Amazon RDS running out of freeable memory. Should I be worried?
It said:
"Short answer - you shouldn't worry about Freeable Memory unless it is became really low (about 100-200 Mb) or significant swapping occur (see RDS SwapUsage metric)."
But My FreeableMemory is 2.9G , and swapUsage is 0 .
Question 1:
Do I need to expand the instance to increase memory? (Modify RDS instance from db.m3.xlarge to db.m3.2xlarge)
Question 2：
Will RDS's Freeable memory continue to decrease until it is less than 100M?
If this happens, what method can I use to make Freeable memory not less than a certain value?
Question 3：
This pictures show innodb_buffer_pool_size:
The value of innodb_buffer_pool_size is {DBInstanceClassMemory*3/4} .
Is innodb_buffer_pool_size related to Freeable Memory?
I Guess:
Total memory - innodb_buffer_pool_size - database memory = Freeable Memory
Am I right?
Question 4：
What parameters of CLoudwatch are used to judge my RDS memory is not enough, Swap usage, Free Memory, Freeable memory?
