"That's a pretty weird analysis, comparing a system that is special purpose with a general purpose one."
I think that's why he says right at the beginning:
This device is that cheap because it cuts
several corners. That's okay for them. But
for general purpose this creates problems.
I want to share my concerns just to show you,
that you can't compare this to a X4540 device.
Let's not forget that BackBlaze started this, by making a graph that compared their prices to S3, etc. (and were also criticised for that in the previous HN thread).
They are talking about cloud storage. Having 3 live copy's of your data in 3 locations is far more important than having lot's of redundancy at a single location. If you want redundancy just add more locations. Large scale company's like Google, Microsoft, and Yahoo understand this but sun is selling feel good hardware to companies that like to think they have unusual needs.
As to speed, nothing you do is going to reduce a disk's low latency so talking about bandwidth is mostly a waste of time. Device bandwidth is rarely the limitation once you start to scale, because you can add devices to your network faster than you can build a better network.
I think that's why he says right at the beginning: