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Comment by userbinator | Hacker News Reader

The 15.36TB PM1633a drive supports one full drive write per day, which means 15.36TB of data can be written every day on a single drive without failure over its five-year warranty.

In other words, assuming good wear leveling, each bit can only be rewritten ~2K times, which is actually quite low for endurance... the capacity is high and they're using that to hide the fact that it's low, but if this was e.g. SLC flash with 100K endurance, you'd be able to write 50x more.

No mention of retention either, which makes me think SSDs today are more for temporary nonvolatile not-quite-RAM storage and not for more permanent applications.

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SLC and MLC endurance aren't much different: http://hothardware.com/news/google-data-center-ssd-research-...

To reach a full rewrite a day, that's like 200Mb/s consistently over the span of a 24 hour day. If your loads/usage looks like this, you're probably expecting your drives to fail and are ready to replace them.

That link says they're not more reliable, which is not at all the same thing.

Given how SSDs work, this is actually pretty good reliability. No one is going to be writing the full disk of 15 TB of data every day.

This disk looks just right for fatcache usage.

They're not guaranteeing failure in 5 years, but are pretty sure it won't fail. If "pretty sure" is 98%, then that's 100K (or something like it, probability maths is hard).

Thet aren't guaranteeing anything. They are saying they will replace it if it fails inside 5 years.

That is a guarantee. That's what "guarantee" means!

But in five years the cost of fulfilling it is low given falling prices.

and that's how companies can afford to offer guarantees.

Outside tech/Moore's Law type companies they offer guarantees by making the products actually durable. A very different model.

No, they offer a warranty. OP used the word guarantee.

A warranty is a guarantee. I used the word "guarantee" as well. It's the right word to use.

Seriously, what do you think a guarantee is?

We guarantee these O-Rings will not rupture.

If these O-Rings rupture, we will replace them under warranty.

> We guarantee these O-Rings will not rupture.

Ah, so you're thinking of a guarantee like a politician would use the word. "I personally guarantee that..."

Every time I hear them say that on TV I'm thinking, "Really? So, what are you going to give me if it doesn't work out? What's that? Nothing?! Then it's not a guarantee is it! You might as well have said you pinky-promise, it would be worth as damn much!"

And then my wife tells me to calm down and stop ranting at the TV.

> If these O-Rings rupture, we will replace them under warranty.

See, that's a guarantee.

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