Rock 4C+ max read/write speed for micro SD and eMMC

#1

Hi guys,

I can’t seem to find what the maximum read/write speed that can be achieved with the Rock 4C+ micro SD and eMMC slot?

Trying to decide if the device can make use of the faster cards like Sandisk High Endurance.

#2

eMMC is way faster than sd card. You will have about 250MB/s compared to 70MB/s on best sd cards. UHS-I cards are limited to 105MB/s, but usually and in real world usage it’s less. UHS-II are not compatible. eMMC modules on sd card (like raspi key) simply don’t work on Rock series (not detected), but they will be limited to sd card slot speed.

Yes, eMMC is much better, not as good as any best ssd/nvme (it’s still less than 1x pcie 2.1 port). It’s just expensive for it’s capacity, new UFS comes with same physical size, much better performance and it’s 2x cheaper.

#3

Thanks for your reply. But I want to know what is the maximum speed capable on the Rock 4.

From the DietPi benchmark I’m only getting about 16MiB/s on a Samsung EVO 64GB card. I don’t know if this is a card limitation or the Rock 4?

#4

This mostly depends on used test method, You may try with not optimal settings (i.e small blocks) or get high speed with not much real usage params. Please note that some i/o devices are cached, so also You can get just fake output.
Max as far as I remember is 105MB/s.

I’m not using diet pi, double check what exactly You are measuring.
Forget about card label, may sound really good, but most cheap cards on market are fake, counterfeit cards. Beside it looks great, has same colors and box with hologram, it’s just poor. And yes, usually You will get about 10MB/s with them.

Try with something that You know it’s working. Check this card on different device.