RDSAvailableMemory #

Meaning #

Alert is triggered when an RDS instance has low available memory.

Impact #

• Performances could be degraded

• Some processes could be killed

Diagnosis #

1. Check the number of database connections

   More

   Database server creates a process for each client. Each process consumes a small amount of memory on the server.

Mitigation #

1. Reduce memory usage

   PostgreSQL

   1. Reduce the maximum number of connections

      Update the max_connections RDS parameter to reduce maximum number of clients

   2. Limit database connections per user

      You can also reduce the maximum number of connections per PostgreSQL user using

      ALTER ROLE <user_to_limit> CONNECTION LIMIT <max_connection_limit_for_role>;
      

   3. Reduce the work_mem

2. Increase server instance type

   Warning: Modifying an AWS instance generates downtime:

   • Multi-AZ enabled: Instance failover will be triggered (< 1 minute downtime)
   • No multi-az: Instance will restarted with new hardware (~15 minutes downtime)

   See AWS documentation

Additional resources #

• https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Troubleshooting.html#Troubleshooting.FreeableMemory