> The Nitro Cards are physically connected to the system main board and its processors via PCIe, but are otherwise logically isolated from the system main board that runs customer workloads.
https://docs.aws.amazon.com/whitepapers/latest/security-desi...
> In order to make the [SSD] devices last as long as possible, the firmware is responsible for a process known as wear leveling.... There’s some housekeeping (a form of garbage collection) involved in this process, and garden-variety SSDs can slow down (creating latency spikes) at unpredictable times when dealing with a barrage of writes. We also took advantage of our database expertise and built a very sophisticated, power-fail-safe journal-based database into the SSD firmware.
https://aws.amazon.com/blogs/aws/aws-nitro-ssd-high-performa...
This firmware layer seems like a good candidate for the slowdown.