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Comment by rcthompson | Hacker News Reader

Even if reads did wear out an SSD, wouldn't it be better to wear them out one at a time rather then wear them all out equally so they all fail in rapid succession once they reach the end of their life cycles?

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On one hand this is true, on the other, if you have two devices that can work for 5 years and then you anyway replace them because they are now too small and never failed you have one device that you replaced and the other hardly in use and you have an increase TCO since you had to buy another device in the middle of the life cycle.

Not that it is really critical, read-disturb exists but it is on a far lower scale compared to erase endurance.

> wouldn't it be better to wear them out one at a time rather then wear them all out equally

Agree and this would seem to make sense.

It is like having two rolls of paper towels in the kitchen. If you use both of them you are only extending the time till empty. If you use one of them only you can then replace that when it runs out running on the 2nd in the time it takes to replace.

I would say no, you'd want the whole disk to fail then so you can just replace it vs. it getting smaller over time, which would make capacity planning pretty complex.

We're talking about RAID1 here, so multiple SSDs. I'm saying you don't want multiple disks to fail in rapid succession, which is what you'd maybe get if you exactly equalized the wear on them.

That makes sense, and you actually do see RAIDs fail like that in the real world sometimes even on non-SSDs.

If the SSD has mechanisms to protect against read disturb, they should also factor that into the life remaining indicator to plan for replacement.

There's no need. If a page has been read enough times to produce a read disturb, the remedy is to re-write the page, which moves the write endurance indicator (by the smallest possible increment).

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