15 ms·
A2-class microSD cards offer no better performance for the Raspberry Pi
- stefan_ 7y agoTesting microSD card speed on a Mac is rather pointless because performance is (severely) limited on the Raspberry Pi through it's terribly slow interface, not necessarily the actual card. Remember RPi 1-3 use a plain SPI interface, and even the new 4 only has UHS-1.
- larrik 7y agoI have no idea what your point is. Testing on a mac is pointless because RPi performance is limited? Except the article showed the exact same performance in both places. It started with: Why don't these cards designed for things like RPi actually show any improvement? Oh, they don't show improvement on any device at all, they are full of crap.
- dkersten 7y agoHe explained in the article why he did this: to check if the manufacturers claims are incorrect, or if its a RPi hardware issue.
- close04 7y agoThe point is if the cards actually meet spec and if they behave differently on the RPi. So the first step is to show how the cards behave in an environment with no artificial performance limitations. This is the baseline "peak performance". The next step is to show whether the RPi's performance ceiling is below that baseline, or if any specific card behave particularly poorly on the RPi. 2 cards may be equal on a high performing machine but for some reason have big differences when running in the RPi.
- monocasa 7y agoRpi1-3 definitely have an MMC controller.
- Dylan16807 7y agoEven at 25MBps, it's very easy to see if you're bottlenecked to less than a thousand 4K writes per second (4MBps), and pretty easy to see if you're bottlenecked to less than three thousand 4K reads per second (12MBps).
- walrus01 7y agoThe 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.
- vorpalhex 7y agoThat'd be an interesting feature to see but I'm sure it'd also really run up the board cost...
- pstrateman 7y agorockpi 4A is $39 and has an m.2 slot https://shop.allnetchina.cn/collections/frontpage/products/rock-pi-4-model-a-board-only-no-wlan-bluetooth-poe https://shop.allnetchina.cn/collections/frontpage/products/r...
- jchw 7y agoWould be nice to see an NVMe slot on one of these things. I’m guessing there aren’t even enough PCI Express lanes on RPi 4 to do that today.
- pingec 7y agoExactly, who cares about speed when all the microSD cards I try eventually become corrupt due to poor controller logic.
- patentatt 7y agoTry an ‘industrial’ flash card. I outfitted my pi with a SwissBit microsd and haven’t had any disk problems since.
- pizza234 7y agoGiven 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-term durability) - again, the XU4 supports a SATA bridge - the Odroid has both eMMC and SATA ports (I mention Odroid purely because I'm familiar with the products)
- module0000 7y agoI appreciate you doing these tests, this (and your last article) instantly answers my question about "how will this perform in one of my rpis?". Please keep doing them as new cards(with their marketing claims) are introduced!
- djsumdog 7y agoI'm surprised we haven't seen a smaller than M.2 form factor for SATA on embedded devices. It seems like the big limiter on devices like the Raspberry Pi and others are the sd cards/emmc modules, since the amount processing power and ram have been continually going up. If you need disk performance on the Pi 4, wouldn't it make more sense to only keep the kernel,initrd on the sdcard and mount the primary filesystem off a USB3 device (like an mSATA-2-USB enclosure), that is if you have the space to spare for it in your project/enclosure? I did something similar with one of the SolidRun devices, but I had to scuttle it due to other hardware problems: https://penguindreams.org/blog/review-clearfog-pro/ https://penguindreams.org/blog/review-clearfog-pro/
- jacobush 7y agoYep. USB disks also are generally much more robust to errors than SD cards. My mail spool is on USB, the OS is on the SD card.
- geerlingguy 7y agoSoon (hopefully) the Pi 4 will be able to completely boot off USB 3.0 devices; right now you can partially boot off an external volume, but /boot still has to be on a microSD card. Though in my testing, it's still not a night-and-day performance difference, if judged by the Pi 3B+. I am not sure if the Pi 4's USB 3.0 port bandwidth will give that much of an improvement. It would be quite nice to have any form of drive supported more directly, NVMe, m.2, whatever.
- NikolaeVarius 7y agoDoes /boot get read/written to enough where this is not "good enough"
- geerlingguy 7y agoIt 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.
- hajile 7y agoSupport for booting from SSD should solve the SD issues before too long.
- gcbw2 7y agowhy things on the RPi take so long? is the SoC still undocumented because of the NDA as before?
- officeplant 7y agoLooks like I'll keep booting my pi's from usb attached storage. At least with the Pi4 USB speed improvements should be nice.
- 542458 7y agoI didn’t even know you could do that! Any idea if it works on the pi4 or not? The docs don’t mention it. https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md https://www.raspberrypi.org/documentation/hardware/raspberry...
- JudgeWapner 7y agojust a guess but s/he may have been referring to just putting root filesystem on a USB drive, but still requiring the bootloader (and possibly kernel?) to be on sd card. It's a one-time "hit" that is completely negligible.
- HankB99 7y agoThat's the present situation and I've used it before. Some recent Pis can boot directly from a USB drive without the need for a bootloader on the SD card. That's still in the works for the Pi 4 as I understand, but network boot (PXE?) will come before that.
- deleted 7y ago[deleted]
- megous 7y agoA2 needs support in the Linux kernel. It's not there, yet. https://github.com/ThomasKaiser/Knowledge/blob/master/articles/A1_and_A2_rated_SD_cards.md 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) support since the host needs to activate those new features first. The cache feature on A2 rated cards makes use of volatile RAM on the card requiring the host to learn new commands to issue flushing the cache (involving the risk of data losses -- for details see especially chapter 4.17 in Physical Layer Simplified Specification 6.0)"
- geerlingguy 7y agoSo 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?
- megous 7y agoI 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.
- ggg3 7y agosd card performance specs are all a joke. they are "at most" some speed. What even is the point of writting such spec? the car analogy would be if you measure some car going down a hill (doesn't even matter if tumbling and killing everyone inside), measuring that it was 300mph and then advertising it as "speeds of 300mph!!!"
- cameronbrown 7y agoAlso how ISP speed is measured ;)
- lostlogin 7y agoIt’s how everything is advertised. Fuel efficiency/mileage, serving suggestions, battery life, investment returns, ‘savings of up to x%’ etc. Unless these things get regulated (and sometimes even if they are) the advert doesn’t really match reality.
- Youden 7y agoAdvertised, not measured. And it's not like that everywhere, the UK has started what I hope develops into a trend: https://www.bt.com/broadband/deals/ https://www.bt.com/broadband/deals/
- tialaramex 7y agoThe averages are basically pointless. They might as well publish average average book lengths for categories on Amazon. Want a young adult novel? Average price 4¢ per page! Oh you want a specific novel? Sorry we advertise averages only. What you'll actually get is determined by factors entirely out of their control. Whether that's an install engineer using a reel of Cat5e because that's what was in the truck even though the work order said crappy Category 3 phone cable would do, or even the neighbours are all using the most expensive package and that causes electrical interference that reduces everybody's bandwidth. You can measure your actual characteristics, and the ISP will offer to do a half decent estimate of that, that's useful to at least decide which service to buy but the average is essentially worthless.
- jokoon 7y agoHow 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.
- gcbw2 7y agosmartphone batteries will go out much, much sooner than a RPi SD card write-life. And nowadays they are much harder to replace.
- deepspace 7y agoThat is just not true. I have burned through many a RPi SD card in 3-6 months, while phone batteries last 2 years at minimum.
- lostlogin 7y agoWhat is your use case for the Pi? That’s a very short lifespan.
- HankB99 7y agoAnd what brand are you buying? FWIW I have several Pis running 24x7 and have not had a single SD card failure. I usually buy high end cards but I also buy cheap cards (4GB cards)and a few Micro-Center house brand, for which I don't know the quality. I've had one that has been running years, I think. Drives a monitor, looping a video where my wife works. The only SD card failure I have experiences was in a camera.
- erik 7y agoIn my experience this isn't caused by exhausting the endurance of the flash. It seems like a lot of SD cards have really buggy firmware. And that Linux running on a RPi is particularly prone to triggering these bugs. Industrial SD cards seem to hold up better. Early iterations of the RPi boards apparently had some bad design choices in the power circuitry, which makes the problem worse.
- tinmandespot 7y agoDoing god’s work
- artemonster 7y agoSD is a garbage spec. Arasan IP for SD host (in Raspberry SoC) is trash. Driver support is minimal. What'd you expect?
- devinjflick 7y agoVery glad I took your recommendation from your previous article on the Evo cards for my new RPi4s! kudos and thank you sir!