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Comment by geerlingguy | Hacker News Reader

tl;dr: the Pi 4 has a much more rosy outlook when it comes to IO both for the microSD card and external drives. The Samsung Evo+ is still the best value for your money.

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I'm surprised by the lack of mention of the A1/A2 "Application Performance Class"[1]. These classes specify minimum performance numbers for random reads and random writes: 1500/500 read/write for A1, 4000/2000 read/write for A2.

Notably, the Amazon link for the Sandisk Extreme points to an A1 version, not the A2 version[2]

  1. https://www.sdcard.org/developers/overview/application/index.html
  2. https://smile.amazon.com/gp/product/B07FCMBLV6

My understanding is that A2 cards are generally slower than A1 cards IF you don't have host-side support for managing the volatile-RAM caching that A2 requires.

So if the Pi 4 only allows you to run in A1 mode anyway, you're better off buying the A1 card and both saving money and getting a faster card. I don't know if that lack of support is true of the Pi 4, but it does seem to be true of most other SBCs according to https://github.com/ThomasKaiser/Knowledge/blob/master/articl...

Ah, interesting, I did not realize there was a difference in protocol. I thought A1/A2 were just spec requirements.

I wonder if A2 support is something that could be added in newer kernels, or whether it requires hardware support.

Let me prefix saying I appreciated your writing. However you didn't test endurance. You only tested throughput (I/O). Throughput isn't the same as performance. Why call it performance?

I had Raspberry Pi's fail from consumer grade microSD cards. Which sucks if its ~4 hrs of travel (one way). This hasn't happened with industrial grade yet. (I buy mine from DigiKey.)

I'm curious about throughput differences with regards to filesystems.

Two ideas for a follow-up.

The 32GB card I have running in the Pi that often hosts www.pidramble.com has been running on a Pi 2, Pi 3, Pi 3 B+, and now Pi 4 for almost four years and has not had any corruption issues.

I also have had a number of other Pis using the Samsung Evo+ and SanDisk extreme cards, many running for one to two years (some doing logging, others saving time-lapse pictures, uploading in batch to an FTP share, then saving more), and have also never encountered a corruption.

I think it has a lot more to do with the power supply than the card itself (as long as you're using a SanDisk, Sony, Samsung, etc. and not some no-name card).

I think the endurance cards have a little better caching mechanism built into the flash controller itself, so they can kind of paper over flaky power supply issues. So yes, it is definitely better to use endurance class cards. But in my experience, I have not encountered an issue using the typical consumer-grade cards.

I've gone through three Samsung EVO sdcards in an Intel NUC. I was using it as a boot drive. All were replaced under warranty. But they each died, becoming read-only, within about 5 months of use.

I don't think these cards are designed as random access devices. I think they're for cameras: video and photos, and also for cell phones, also mostly video and photos, maybe some app offloading also.

It is not, it's pretty much equal to Sandisk Ultra A1 in performance. (not the same as the one tested in this test)

You can get original 32GB Sandisk Ultra A1 for $4.30 (or $8 incl. shipping) on aliexpress.

Evo+ is $8.60 (or $15.79 incl. shipping) on Amazon.

Do you trust a microSD card you've bought off Aliexpress? Because I wouldn't. It's questionable if you can even trust one purchased from Amazon, but buying off Aliexpress is next level skeezy. There are a vast amount of fake/counterfeit microSD cars on the marketplace, so this argument is pretty silly if you ask me.

See above.

https://news.ycombinator.com/item?id=20403155

I wouldn't write the comment if I wasn't 100% sure the cards were original. Yes, you can get original Sandisk cards from aliexpress for that price, and actually verify it on the manufacturer's website. You can't do that for Samsung.

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