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Comment by vardump | Hacker News Reader

Narrow bus? I think current SD card standards can go way past 1GB per second (note: see edit below). It's an implementation detail.

In practice, these cheap boards will have a cheap eMMC soldered in that can't do these fancy things anyways. It's not going to be same quality chip like in flagship phones.

Once that cheap eMMC fails, the device is bricked.

Edit: SD card standards still can't go past 1 GB/s, max 985 MB/s. Either way, plenty for cheap SBCs.

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SD cards as present on Raspberry Pi, even the Pi 4, don't go beyond ~60MB/s. Older Pis get around ~20MB/s. It's the worst bottleneck of the system. Where do you get that 1 GB/s figure from?

Oh yes, another one of my pet peeves with Raspberry Pi: ancient slow SD implementation.

https://en.m.wikipedia.org/wiki/SD_card

SD Express can do up to 985 MB/s.

SD UHS-II @300MB/s would be plenty for most SBCs.

Do be aware that the Pi 4 increased the SD Card Reader speed, almost by double, I hear.

Sure, but I still can't even use my 5-6 years old Samsung Pro microsd 64 GB card at full speed, 90-100 MB/s read & write!

Bear in mind that SD Express is SD only in name and otherwise it is just an NVMe in SD form-factor. And how much UHS-II is still an SD is somewhat questionable.

True. But on the other hand similar to how for example USB standard has developed from USB 1.0 to USB 4.

While it would technically be correct, no one says new USB standard X is USB in name only.

Perhaps every data transfer interface standard eventually adopts a PCI-e lane. :-)

Remember that on a Pi, you can boot from a USB flash drive or Network...

This is more like, you should. Because the SD interface sucks.

odroid boards use a modular eMMC design. You can buy the size you want and swap them out if one fails. You can even see that in their picture (label M).

https://www.hardkernel.com/shop/odroid-c4/

They sell their eMMC chips here

https://www.hardkernel.com/product-category/memories/

I don't think even flagship phones have "quality chip" inside. Phone OS's are still running without swap memory support to cope with poor quality of their onboard eMMC (which leads to OOM-killing "background" apps instead of just swapping memory out.)

iPhones use NVMe storage and have done since the iPhone 6S and the quality of the NAND chips has been increasing since the iPhone 6.

narrow as in bit width

So blame the bad narrow implementation?

Not taking sides, just trying to clarify. I think there's a place for eMMC and SD but you're right chip quality and controller implementation is key.

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