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Comment by mkoubaa | Hacker News Reader

Dumb question. Why does the network have to be slow? If the SSDs are two feet away from the motherboard and there's an optical connection to it, shouldn't it be fast? Are data centers putting SSDs super far away from motherboards?

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It’s not the network being slow, but dividing the available network bandwidth amongst all users, while also distributing the written data to multiple nodes reliably so that one tenant doesn’t hog resources is quite challenging. The pricing structure is meant to control resource usage; a discussion of the exact prices and how much profit AWS or any other cloud provider makes is a separate discussion.

What happens when your vm is live migrated 1000 feet away or to a different zone?

> One theory is that EC2 intentionally caps the write speed at 1 GB/s to avoid frequent device failure, given the total number of writes per SSD is limited.

This is the theory that I would bet on because it lines up with their bottom line.

But the sentence right after undermines it.

> However, this does not explain why the read bandwidth is stuck at 2 GB/s.

Faster read speeds would give them a more enticing product without wearing drives out.

They may be limiting the read artificially to increase your resource utilization else where. If you have disk bottleneck then you would be more likely to use more instances. It is still about the bottom line.

That could be. But it's a completely different reason. If you summarize everything as "bottom line", you lose all the valuable information.

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