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Comment by wtallis

2 years ago

> When one cell is read in the vertical stack, the interferences produced by the traces in the area increases the cells that need to be rewritten, what consumes the life of the device, by design.

You should try being honest about the magnitude of this effect. It takes thousands of read operations at a minimum to cause a read disturb that can be fixed with one write. What you're complaining about is the NAND equivalent of DRAM rowhammer. It's not a serious problem in practice.

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wtallis

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drtgh  2 years ago

Not NAND equivalent as the larger the stack, the larger the writings on the continuous cells, not just rewriting a single cell.

Here, the dishonest are the SSD manufacturers of the last decade, and they are feeling so comfortable as to introduce QLC into the market.

> It's not a serious problem in practice.

It's as serious as in to read data consume the disk, and the faster its read the faster it's consumed [0]. You should have noticed that SSD disks no longer come with a 10-year warranty.

    "under low throughput read-only workloads, SSD-A/-B/-C/-D/-E/-F extensively rewrite the potentially-disturbed data in the background, to mitigate the read (disturbance) induced latency problem and sustain a good read performance. Such rewrites significantly consume the already-reduced SSD lifetime. "

Under low throughput read-only workloads.

It is a paper from 2021, what means sci-hub can be used to read it.

[0] https://dl.acm.org/doi/10.1145/3445814.3446733

  • wtallis  2 years ago

    > It's as serious as in to read data consume the disk, and the faster its read the faster is consumed

    Numbers, please. Quantify that or GTFO. You keep quoting stuff that implies SSDs are horrifically unreliable and burning through their write endurance alarmingly fast. But the reality is that even consumer PCs with cheap SSDs are not experiencing an epidemic of premature SSD failures.

    EDIT:

    > You should have noticed that SSD disks no longer come with a 10-year warranty.

    10-year warranties were never common for SSDs. There was a brief span of time where the flagship consumer SSDs from Samsung and SanDisk had 10-year warranties because they were trying to one-up each other and couldn't improve performance any further because they had saturated what SATA was capable of. The fact that those 10-year warranties existed for a while and then went away says nothing about trends in the true reliability of the storage. SSD warranties and write endurance ratings are dictated primarily by marketing requirements.