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Comment by chaos_a | Hacker News Reader

sounds like people simply weren't taking any care of them, that's why they broke. If they had cases and decent sd cards that probably wouldn't have happened.

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I’m responsible for a fleet of a few hundred Raspberry Pis being used as home monitoring hubs - they use high grade SD cards, and are configured to write as little as possible while still fulfilling their function, yet we still see one or two a month fall of the internet because of SD card corruption. This is absolutely a problem.

I believe the compute module is somewhat better in that it uses eMMC rather than SD cards.

Correct me if I’m mistaken, but isn’t eMMC literally just an embedded SD card?

It is, and it is better because it probably has better chips, but it will die, and brick RPi in the future.

As someone who has also worked with fleets of devices (R.Pi-based and others) working off SD-cards, I can confirm what jon-wood is saying. For some reason SD cards fail at a much higher rate than eMMC flash chips in traditional SMT packages.

Same interface as an SD card, but better firmware and probably higher quality flash. SD cards are really aggressively cost-cut, often coming in than less than the price of raw flash of the same capacity.

School computers take a beating. That's why the two are incompatible.

That's one of the reasons the Apple II was so popular with schools.

It was built like a tank.

The Bell & Howell version came in Darth Vader black too: http://www.digibarn.com/collections/systems/appleII-bell-and...

Interesting it was painted and not a differently colored plastic.

SD cards with wear leveling and error correction are hard to find and can easily be more expensive than similar SSDs.

I was under the impression most non-awful SD cards had some sort of wear-leveling these days but there's no standard for it so they don't advertise it on the front like SSDs. I couldn't really find any proof either-way about this, just a few instances of people looking into it:

- https://electronics.stackexchange.com/questions/27619/is-it-... - https://www.reddit.com/r/raspberry_pi/comments/ex7dvo/quick_...

I think every microSD and USB sticks by now has WL across the board, especially at awful grade. WL and ECC are must at current [price, BER, capacity, bit-per-cell] or something.

With USB sticks it's a different story. There are some manufacturers like Sandisk who claim they use wear leveling in all of their current USB sticks.

microSD is a mess in this regard. Wear leveling is less common there and only present in very specific and expensive niche models.

[citation needed]. I can’t believe any but the cheapest no-name SD cards would have absolutely no form of wear leveling.

It does look like there are many of cards that don't claim any sort of wear leveling (doesn't mean they don't do it at all but they don't call it out). This is surprising to me, but if you want to make sure you get a card with wear leveling, look for it in the specs. These SanDisk industrial cards[1] are ones I've used in the past that specifically claim they do wear leveling in the spec sheet: Advanced memory management FW features power immunity, auto/manual read refresh, ECC, wear leveling. They're also only a few bucks more than a "normal" microSD card.

[1]https://www.amazon.com/SanDisk-Industrial-MicroSD-UHS-I-SDSD...

Too many kids, that's the problem with schools these days.

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