RDS Aurora ServerlessV2 Global pricing clarification


Hello, I want to setup an RDS Aurora PostgreSQL ServerlessV2 Global set up running in us-east-1 and us-west-2. With two instances total, the us-east-1 one being the read/write, and us-west-2 one being the read only.

I understand that I need to set my minimum capacity to 8 ACUs for Global ServerlessV2 instances, that is clear to me from the docs.

I need clarification on when I am charged. If my system is sitting idle and not running any DB operations whatsoever, am I still charged at 8 ACUs? In other words, if my system is provisioned/enabled/active but just idle so not in use at the moment, am I still charged at my minimum capacity level?

Clarification here would be amazingly helpful, the docs are NOT clear on this whatsoever. At on place they say that you're not charged, at another place they say that you are charged.

2 Answers

Hey Kyle,

Here's what is mentioned in the Serverless documentation[1]: If your provisioned workload has memory requirements that are too high for small DB instance classes such as T3 or T4g, choose a minimum ACU setting that provides memory comparable to an R5 or R6g DB instance. In particular, we recommend the following minimum capacity for use with the specified features (these recommendations are subject to change): Performance Insights – 2 ACUs Aurora global databases – 8 ACUs (applies only to the primary AWS Region)

Now, I can tell you that Performance Insights is definitely wanting 2 ACU/4gb because you need extra RAM to store the performance_schema tables Performance Insights requires. The 8 ACU is precisely in line with the memory requirements for provisioned instances - the r5.large is 2 vCPU and 16gb, and 8 ACU is the same 16gb of RAM. So they're asking roughly the same specifications.

They are recommendations, not absolute rules, so you can go lower, though it does risk out-of-memory errors, and problems with slower than expected replication. It's important to remember to ask how much money might be saved, and how much a crash or restart might affect your application. If it's a new application, still being tested, you can probably afford a lot of scaling up (then back down), and/or the occasional crash. If it's for production, you'd want to measure the cost savings versus the costs of a crash or OOM error.

In regards to the AWS pricing calculator please know that the charges for Aurora Serverless v2 capacity are measured in terms of ACU-hours. This is calculated by the average # of ACU's used per hour. For example, if on average every hour you use 4 ACUs for 30 minutes and 2 ACUs for the other 30 minutes each hour would be 3 ACU's. How you calculate this estimate is entirely based on your workload and how often it scales up/down ACUs. Please take a look at the following documentation for more examples on how this estimation process works [2].

Please note in addition to ACU’s used per hour you will be charged for storage rate and I/O rate. For Aurora Standard in US-East-1 you are charged $0.10 per GB-month and $0.20 per 1 million requests. For more information on these prices please view here [3].

Also if you leave the instance running it will continue to use the minimum ACU value that you configured for this cluster. As per Doc [4] “Aurora Serverless v2 writers and readers don't scale all the way down to zero ACUs. Idle Aurora Serverless v2 writers and readers can scale down to the minimum ACU value that you specified for the cluster.”

References: [1]https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.setting-capacity.html#aurora-serverless-v2.min_capacity_considerations [2]Aurora Pricing Examples: https://aws.amazon.com/rds/aurora/pricing/#:~:text=Japanese%20Consumption%20Tax.-,Aurora%20pricing%20examples,-The%20following%20examples [3]Amazon Aurora Pricing: https://aws.amazon.com/rds/aurora/pricing/ [4]https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.how-it-works.html#aurora-serverless-v2.how-it-works.scaling

answered 3 months ago

hi Kyle,

Hope you are well. Maybe you find global database serverless v2 pgsql capacity that config ACUs set to 8 (https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.setting-capacity.html), Actually, Serverless v2 price base on capacity(ACUs)/seconds, the smallest ACU is the smallest billing specification of the cluster in the current month, and new fees will be added as the ACUs is elastic.

Meantime, you can also configure the smallest ACUs according to your own practice

answered 3 months ago

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