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Goural
Goural

Reputation: 79

Downsizing AWS RDS database instance based on cloudwatch metrics

I have postgresql RDS db in AWS of size db.t3.large with 50gb vol. For cost reduction I am looking into reducing the instance size to db.t3.medium. Below are the cloudwatch metrics

Question 1: I want to understand based on the below metrics if I can downsize instance to db.t3.medium without any issues.

Question 2: Can I simply modify/downsize the RDS instance from db.t3.large to db.t3.medium from AWS console without any data loss?

FreeStorageSpace - 49G
    
FreeableMemory - 5.3G
CPUUtilization - 3.4%
ReadThroughput - 10k-170k
NetworkReceiveThroughput - 6k   
NetworkTransmitThroughput- 250k
WriteIOPS- 10
ReadIOPS - 2
CPUCreditUsage - 0.403

Upvotes: 0

Views: 49

Answers (1)

luanmateuz
luanmateuz

Reputation: 83

Based on your RDS usage metrics, it seems feasible to downgrade to the db.t3.medium. I’m assuming these metrics represent at least a month of usage. CPU, memory, and network utilization are all low, which suggests that your current instance resources can be reduced without major issues. The only thing to watch out for is the WriteIOPS and ReadIOPS metrics. While these values are low, if there is a spike or intensive usage of these operations, it could lead to performance degradation. However, based on your current metrics, it seems unlikely that this will be a problem.

If you are using gp3 storage (General Purpose SSD), the IOPS and throughput capabilities are more flexible, allowing for easy adjustment as needed. So, if you experience IOPS spikes or require more storage performance in the future, you can increase these configurations without needing to change the instance type.

It’s also a good idea to monitor the RDS usage for some time after the downgrade. If the usage continues to remain low, you might consider downgrading further to a db.t3.small, or you could explore the possibility of switching to t4g instances. T4g instances offer better price/performance ratios for workloads with low and burstable CPU demands, so they could be a great option if your workload is light.

Changing the instance type is simple and can be done directly through the AWS console. However, keep in mind that there will be a brief downtime during the process, so it’s important to perform the modification during a time of low database activity.

Upvotes: 0

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