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A2-class microSD cards offer no better performance for the Raspberry Pi

jeffgeerling.com

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Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#41

Post by megous »

geerlingguy wrote: post #38
megous wrote: post #35

A2 needs support in the Linux kernel. It's not there, yet. https://github.com/ThomasKaiser/Knowledge/blob/master/articl... "A2 promises even better performance with 4000/2000 read/write IOPS minimum but there's a problem since as outlined by the SD Association A2 cards show "much higher performance than A1 performance by using functions of Command Queuing and Cache". Cache and Command Queuing require host (driver) su…

So is there any kind of device able to use A2 cards at the rated performance yet? I can't get anything better on my Mac with multiple readers (USB 3.0 and 3.1), and I'm guessing if I tried on the reader in my 1 year old Dell XPS, I'd get the same. What good is a performance designation (A2) if no device in the real world supports it?

I don't know. It's a bit of a bummer.

I imagine Android would benefit the most (and phones also don't suffer from sudden power outages, which is the biggest risk with enabling this), so someone may try looking if mmc core in androind kernel has patches to support this.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#42

Post by xeeeeeeeeeeenu »

walrus01 wrote: post #3

The major problem is not disk write speed, which we can all agree sucks, but longevity and lifespan when used as a system boot disk and also containing /var and similar. The write wear leveling on a u3 microsd card is nowhere near as good as even a $50 consumer class ssd. Small single board computers should move towards m.2 2280 nvme drive support, or at least one sata 6 gbps interface.

If you want longevity, but an SLC card.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#43

Post by geerlingguy »

kup0 wrote: post #31
geerlingguy wrote: post #29

Earlier quoted context omitted.

It doesn't, but in my informal tests (I haven't had time to set up a thorough benchmark) real-world usage of an external USB 3.0 SSD (testing with a cheap Kingston SSD, though, and a cheap USB SATA interface) is only marginally faster than a Samsung Evo+ microSD card.

I wonder if this is also due to the fact that many desktop SSDs do not focus on 4k read/write performance. This is one big area where nvme SSDs seem to have an advantage, their 4k read/write is usually significantly higher than that of other SSDs (at least from benchmarks I've seen). Maybe even a lower end nvme ssd + usb enclosure would be the way to go to get the best performance. Unless there's something about the…

True; some of the cheapest SSDs I've tested seem to just be the same package that would be inside a USB flash drive or SD card, hardwired to an SATA plug in a giant 2.5" enclosure!

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#44

Post by pizza234 »

pizza234 wrote: post #10
walrus01 wrote: post #3

The major problem is not disk write speed, which we can all agree sucks, but longevity and lifespan when used as a system boot disk and also containing /var and similar. The write wear leveling on a u3 microsd card is nowhere near as good as even a $50 consumer class ssd. Small single board computers should move towards m.2 2280 nvme drive support, or at least one sata 6 gbps interface.

Given the market segment, theoretical longevity and lifespan are not a concern - both on the producer side, who has to put more expensive chips, and on the consumer side, who has to pay for the chips and the media (SD cards are extremely cheap). Moving up in the market segnment there are in fact higher-end solutions: - the Odroid XU4 has an eMMC port (for those who want a compact solution but don't care about long-te…

Corrections:

  - the Odroid XU4 has an eMMC port [...] a compact *and faster* solution [...]
  - the Odroid *H2* has both eMMC and SATA ports

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#45

Post by jokoon »

How about lifespan? I fail to understand why SD card have such a short lifespan, and it's the sole reason I won't acquire an RPi.

It seems that the only think that is lacking on RPi is flash memory storage. Most smartphones have a lot of it, and it seems that 1GB of storage would be enough for the RPi and would not necessarily be so expensive.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#46

Post by gcbw2 »

jokoon wrote: post #45

How about lifespan? I fail to understand why SD card have such a short lifespan, and it's the sole reason I won't acquire an RPi. It seems that the only think that is lacking on RPi is flash memory storage. Most smartphones have a lot of it, and it seems that 1GB of storage would be enough for the RPi and would not necessarily be so expensive.

smartphone batteries will go out much, much sooner than a RPi SD card write-life. And nowadays they are much harder to replace.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#48

Post by mikepurvis »

giobox wrote: post #14
walrus01 wrote: post #3

The major problem is not disk write speed, which we can all agree sucks, but longevity and lifespan when used as a system boot disk and also containing /var and similar. The write wear leveling on a u3 microsd card is nowhere near as good as even a $50 consumer class ssd. Small single board computers should move towards m.2 2280 nvme drive support, or at least one sata 6 gbps interface.

The Pi steals the lion’s share of the attention the in the cheap SBC space, but there are plenty of alternatives that have better storage solutions out there. I too grew fed up of SD card issues. I always see the argument “but the Pi has the best community support!” trotted out, and I don’t disagree. However, it’s all normally just sane Linux distros on the Pi at the end of the day. Whatever instructions/advice someo…

I think it depends a lot on your use case. If you just want a dirt cheap HTPC, then yes, there are lots of SBCs that will fit the bill, but the RPi also has a hardware add-on ecosystem around its particular camera and GPIO/SPI/I2C/I2S availability, and even though lots of other boards have those things available and broken out too, you're going to have to be willing to do a lot more leg work to get it all hooked up properly and working for a different SoC.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#49

Post by throw20102010 »

jokoon wrote: post #45

How about lifespan? I fail to understand why SD card have such a short lifespan, and it's the sole reason I won't acquire an RPi. It seems that the only think that is lacking on RPi is flash memory storage. Most smartphones have a lot of it, and it seems that 1GB of storage would be enough for the RPi and would not necessarily be so expensive.

I can't help you with the why some SD cards are short lived, but if you want a longer lasting SD card, try the "endurance" versions. Most of the big brands have a version. They are a bit more expensive, but promise 25x the write life of a standard SD.

They are typically marketed toward video surveillance systems and dash cams. I'm not sure how the rest of a Raspberry Pi's performance would be effective.

Re: A2-class microSD cards offer no better performance for the Raspberry Pi

#50

Post by Vogtinator »

joshvm wrote: post #12
walrus01 wrote: post #3

The major problem is not disk write speed, which we can all agree sucks, but longevity and lifespan when used as a system boot disk and also containing /var and similar. The write wear leveling on a u3 microsd card is nowhere near as good as even a $50 consumer class ssd. Small single board computers should move towards m.2 2280 nvme drive support, or at least one sata 6 gbps interface.

SD card performance on the Pi Jeff's benchmarks are accurate in my experience. If you try saving single images from a camera at even 5-10fps, the card quickly bottleneck and you start dropping frames. If you buffer and store (in my case 16-bit raw), you can essentially saturate USB bandwidth if you're also using a USB camera.

No, the bandwidth isn't shared as both sd controllers (sdhci and sdhost) are directly accessible using MMIO (and DMA).
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