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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

#61

Post by lostlogin »

cameronbrown wrote: post #40
ggg3 wrote: post #37

sd 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!!!"

Also how ISP speed is measured ;)

It’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.

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

#62

Post by HankB99 »

deepspace wrote: post #57
gcbw2 wrote: post #46

Earlier quoted context omitted.

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

That 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.

And 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.

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

#63

Post by rhardih »

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.

The Pi doesn't necessarily need an SD card. I'm running it on NFS, booted over the network. Works just fine. No need to worry about burning out the SD card.

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

#64

Post by aidenn0 »

megous wrote: post #41
geerlingguy wrote: post #38

Earlier quoted context omitted.

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.

My phone will reboot randomly; depending on what layer the reboot happens at, there may be no flush command sent to the card.

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

#65

Post by cat199 »

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?

> What good is a performance designation (A2) if no device in the real world supports it?

this is often the case for new hardware specs/protocols..

see also: any SATA/SCSI rev N+1, TCQ/NCQ, UASP, PCI n+1, etc.

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

#66

Post by vardump »

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.

FWIW, only noname and Sandisk cards have given up the ghost on me. Samsung Pro & Evo cards have been doing just fine. Other than that, you just need to worry about getting proper power. Just use the official power supplies, and you're fine.

Also eMMC chips are no magic. There are crappy ones and good ones. Guess which ones you're going to get for little money?

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

#67

Post by erik »

deepspace wrote: post #57
gcbw2 wrote: post #46

Earlier quoted context omitted.

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

That 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.

In 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.

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

#68

Post by jononor »

elcritch wrote: post #53
jononor wrote: post #33

Earlier quoted context omitted.

Solder the microSD and use the solder-points for thermal connection to the board, like for most other medium-power ICs. It is also cheaper than a socket.

Can standard microSD's survive standard reflow soldering? I wouldn't think they survive, but would be nice.

Unfortunately I have not found microSDs suitable for reflow soldering. Typically one uses eMMCs instead, which are very similar, but has a much higher price (and reliability).

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

#69

Post by HankB99 »

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.

> ... and it seems that 1GB of storage would be enough for the RPi and would not necessarily be so expensive.

Enough for what? A typical Raspbian install not takes a bit more than 4GB. I don't think that the Lite version (no GUI or applications) would fit either. I'd suggest 8GB, if that's a convenient size. As flash density increases, more and more goes on a single chip and that's where production is going. Consider the price of SD cards or USB sticks. Below about 16 or 32GB they don't get much cheaper and I suspect is is for this reason.

And IAC, the RPi foundation is working hard to keep the price of the board at $35US so adding something like this probably means something else would have to be eliminated.

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

#70

Post by blackflame7000 »

vardump wrote: post #66
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.

FWIW, only noname and Sandisk cards have given up the ghost on me. Samsung Pro & Evo cards have been doing just fine. Other than that, you just need to worry about getting proper power. Just use the official power supplies, and you're fine. Also eMMC chips are no magic. There are crappy ones and good ones. Guess which ones you're going to get for little money?

Proper power is essential. A phone charger is not a power supply even though it works. I suspect a lot of SD cards are getting undeserved blame from a PSU issue.
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