GP2 vs GP3 RDS storage mechanics - how it works - bottleneck, metric to watch, how to purchase more

Question

Hello,

I am relatively new to AWS and I will be switching our DB storage from GP2 to GP3 . But before I do it I'd like to ask how it works.

**What I know about GP2:**

* the bottleneck is IOPS - maximum possible is 3000 IOPS
* you can use up to 3000 IOPS until you run out of BurstBalance
* BurstBalance starts to decrease when you use more than your BaseLine IOPS
* BaseLine IOPS = 3 * (volume size in GiB) = 3 * 250 GiB (in my case) = 750 IOPS - then it starts to eat BurstBalance

That's actually everything I need to know. I know the bottleneck, I know how to monitor that, I know what to do in case I need more IOPS. This knowledge cost me about 2 years of trial and error. I'd like to shorten this period by this question with GP3.

**In terms of GP3:**

1. What is the bottleneck? I read something about EBSByteBalance but I haven't understood it.
2. What metric should I watch?
3. What to do when this metric is about to run critical? How much will it cost?

Deeksha · Accepted Answer

Here are the key points regarding the transition from GP2 to GP3 storage for your Amazon RDS database:

1. Bottleneck and Metrics:

The main bottleneck for GP3 volumes is the EBSByteBalance metric, which represents the percentage of throughput credits available.
   You should monitor the EBSByteBalance metric to ensure your workload does not exceed the provisioned throughput.

2. Provisioning GP3 Storage:

With GP3, you can provision the desired IOPS (up to 16,000) and throughput (up to 1,000 MiB/s) independently of the storage size.
   For RDS for SQL Server, you can provision additional IOPS and throughput for any available storage size.
   You pay only for the additional provisioned IOPS and throughput beyond the baseline of 3,000 IOPS and 125 MiB/s.

3. Handling Capacity Needs:

If the EBSByteBalance metric approaches a critical level, you can increase the provisioned throughput by modifying the RDS instance.
   The cost for additional provisioned throughput is $0.04 per provisioned MiB/s-month.

4. Transition Process:

Transitioning from GP2 to GP3 storage is a straightforward process and does not involve any downtime or reboot.
   The RDS instance will enter a "Storage Optimization" state during the transition, but it will remain accessible and you can continue 
   regular operations.

GP2 vs GP3 RDS storage mechanics - how it works - bottleneck, metric to watch, how to purchase more

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