I tested 25+ microSD cards in the 5B if it helps anyone!

#21

No, no. Not that bad… :rofl:
I just wanted to know what benchmark or quick test you ran to compare to my Nvme(s).
Running a complete f3 test and filling up the SD card, Nvme or eMMC gives an accurate picture.
But i don’t advise running it on eMMC, i lost 2 eMMC (32 GB) in one month (each). It was running on an early dev board, maybe there was some kind of overvolting and they fixed it on later versions.

#22

TRIM is unfortunately another feature supported by recent SD cards, but not the Linux kernel. (The feature itself is present, but locked to eMMC only, and never enabled on SD cards.)

BTW, for command queuing, the situation is a bit worse: not only is it only enabled for eMMC, but also only for hosts that can manage the queue entirely in hardware. The Linux kernel itself will never issue CMD44/45 queued requests from software.

There has been a patch proposed to implement software management of native MMC queuing (though not SD), unfortunately it got straight up ignored on the mailing list: https://patchwork.kernel.org/project/linux-mmc/patch/1601195766-26648-1-git-send-email-gray.jia@mediatek.com/

#23

Yeah, a lot missing on the software side of things wrt SD cards and Linux. As for TRIM I forgot something important in my above list how to ‘correctly buy SD cards to be used with SBC’: that’s after verifying capacity with f3write/f3read to always use SD Association’s ‘SD Formatter’ (unfortunately not available for FOSS operating systems) to ‘format’ cards again since this implements CMD38 to tell the card’s controller the whole storage being empty again.

Or do you know something better and also working from within Linux (since the last time I visited this area was 6 years ago).

#24

The samsung A2 Pro Plus and A2 EVO are strangely slower and not A2 spec if you test them with the Samsung USB adapter that comes in the pack. (Which I purchased just to make sure).

I haven’t read up or tested but all my A1 cards seem faster in operation than ‘expensive’ Samsung A2 as budget https://www.mymemory.co.uk/mymemory-plus-32gb-micro-sd-card-sdhc-4k-a1-uhs-1-v30-u3-adapter-100mb-s-3-pack.html are faster.

I guess maybe the samsung USB adapter they supply with there A2 cards isn’t UHS-1 and why maybe they suck and don’t seem to match specs?

#25

It’s probably not a UHS issue, rather, the Samsung adapter probably also doesn’t implement queuing and caching, required for proper performance on A2 cards.

#26

Yeah maybe but when you do by a combo from the Samsung store you might think it could :slight_smile:

https://www.amazon.co.uk/dp/B09D3MNRGH?psc=1&ref=ppx_yo2ov_dt_b_product_details

#27

SDs are subject to wear. If you want to keep your device going for a long time get one of the endurance cards

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