omikron
Posts: 15
Joined: Sat May 25, 2019 8:30 am

Maximum SD card interface speed

Sat Jun 20, 2020 12:04 pm

Hello,

Technical question: What is the maximal speed of SD card interface in PI3 and Pi4 SoC?

Is it a good idea to use high speed cards, designed for 4K video cameras? They're designed for handling videos at 30Mbit or more on the fly.

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rpdom
Posts: 18010
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Maximum SD card interface speed

Sat Jun 20, 2020 12:16 pm

Others will probably reply with better details soon, but generally A1 rated cards are the best.

Cards designed for high quality cameras aren't always the best as they are aimed at constant streaming of data to one file, not random read/writes all over the place.

For the Pi 4, I think a USB3.0 SSD drive would give better performance than an SD card, especially as the USB boot option is getting close to general release now.
Unreadable squiggle

fruitoftheloom
Posts: 25298
Joined: Tue Mar 25, 2014 12:40 pm
Location: Delightful Dorset

Re: Maximum SD card interface speed

Sat Jun 20, 2020 12:20 pm

omikron wrote:
Sat Jun 20, 2020 12:04 pm
Hello,

Technical question: What is the maximal speed of SD card interface in PI3 and Pi4 SoC?

Is it a good idea to use high speed cards, designed for 4K video cameras? They're designed for handling videos at 30Mbit or more on the fly.

A1 is recommended, see:

https://www.raspberrypi.org/blog/sd-card-speed-test/
The information is out there....you just have to let it in.

My other Linux machine is a ChromeBox

Brad Q
Posts: 105
Joined: Mon Aug 12, 2019 12:10 am

Re: Maximum SD card interface speed

Mon Jun 22, 2020 7:41 am

IF I remember correctly the chip for the SD card reader is limited to 40MB/s and the USB chip is limited to 350MB/s(total, Pi4). Jumping from a 100MB/s flash drive to a 300MB/s USB SSD drive(Sandisk) made a HUGE improvement in daily desktop performance.

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jahboater
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Location: Wonderful West Dorset

Re: Maximum SD card interface speed

Mon Jun 22, 2020 8:25 am

Brad Q wrote:
Mon Jun 22, 2020 7:41 am
IF I remember correctly the chip for the SD card reader is limited to 40MB/s
The Pi4 model has doubled the SD card access speed.
Pi4 8GB and Pi4 4GB running Raspberry Pi OS 64-bit

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bensimmo
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Location: East Yorkshire

Re: Maximum SD card interface speed

Mon Jun 22, 2020 9:16 am

The Pi4 is quicker, about 40 to 45MB/s
The 3B+ (and older Pi) when using the overclocking (SD card) feature gets similar and is a bit nippier iirc.

All of this is SD cad dependant of course and 4k and write are the most hit by the ability of the SD card.

If you want to look into comparisons and compare your, look at PiDramble (runs off for a link, http://www.pidramble.com/wiki/benchmarks/microsd-cards )
Have a look there.

There is also James Chamber site were people can banchmark and upload results.
It's a bit hard to navigate and comparing or listing results for specifics doesn't seem possible, that or I've not worked out how..
but it is there anyway. You can see SDcard, usb, ssd etc.
https://storage.jamesachambers.com/


Is that enough or do you still need the actual interface connections ?

Brad Q
Posts: 105
Joined: Mon Aug 12, 2019 12:10 am

Re: Maximum SD card interface speed

Mon Jun 22, 2020 9:53 am

https://www.raspberrypi.org/documentati ... minary.pdf

Page 11:

"Raspberry Pi 4 Model B DatasheetCopyright Raspberry Pi (Trading) Ltd. 20195.1.3 Display Parallel Interface (DPI)A standard parallel RGB (DPI) interface is available the GPIOs. This up-to-24-bit parallel interface cansupport a secondary display.5.1.4 SD/SDIO InterfaceThe Pi4B has a dedicated SD card socket which suports 1.8V, DDR50 mode (at a peak bandwidth of 50Megabytes / sec). In addition, a legacy SDIO interface is available on the GPIO pins."

So Peak is 50MB/s but day in day out is going to be closer to 40.

While my numbers MAY be a little off, if you did into the specifications deep enough, they are pretty close.

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