Why is AWS Aurora Write IOS high at all times?

Question

In AWS RDS Aurora - Monitoring section we notice that, even though most time there is no database activity (according to Monitoring and Performance Insights),

We still notice that for the past weeks,

• Aurora Write IOPS was high at all times
• Aurora Write Latency was high at all times (multiple 100s of ms to seconds)

Why could this be? What could caue the Write IOPS saturation? There is no Database activity that we can see.

Answer 1

There is a bug in the metric. Anyway, In case of AWS Aurora, the writes are done only in memory and to the storage cluster. Inspecting the write latency on the storage cluster, using SSD, is 1ms per write. It is still concerning that the EBS (in our case) write latency on the DB instance is high but the database storage (logs, pages) is not on instances disk or volume or EBS, but only in discs on the storage cluster. So it is a bit less concerning and less impacting on the INSERT or COMMIT latency.