Class U1 vs. U3 uSD Cards

[ScottTX]

Fast Card: (U3)



Slower Card: (U1)



Notice that it's the Write Speed that is different.

 

[ScottTX]

Official DJI Approved List:

 

[ScottTX]

My Test Setup
The uSD to USB 3 interface adapter is capable of 104MB/s This is also a limitation of the UHS-I interface on the uSD cards that we are discussing. (SDR104)
It is connected to a USB 3.2 Gen 1 Acroname Programmable Industrial Hub.
The Hub is connected to a USB 3.1 Gen 1 Port on the PC.
The PC is a Gaming Pro Carbon Motherboard with a Ryzen 7 2700X CPU.

 

[eEridani]

Keep in mind the adapter used to connect the uSD card to your computer affects the benchmark. I have several different adapters, and the speeds shown for my faster uSD cards are all over the map. Are the adapters USB 2.0, USB 3.0, USB 3.1g1, or USB 3.1g2? Plus, are they rated A1 or A2, etc. Most adapters don't say. Only testing against better adapters will reveal their incompetence.

Here's a test I did of my faster uSD card - a Samsung Pro V30 - in five different uSD card readers. The only difference is the reader. Data is from Crystal Disk Mark, best of 5 runs of 256MB data. Not all uSD readers are created equal.

MB/s​	Syrox uSD to USB​	CanaKit uSD to USB​	Sabrent uSD to USB3​	Sandisk uSD to USB3​	Samsung uSD to USB3​
Read	18.7​	19.1​	97.3​	97.3​	158.8​
Write	17.4​	17.4​	86.4​	85.3​	120.2​

 

[ScottTX]

1 The uSD Reader that I use is a USB 3.0 device.
2 What is the model number of the Samsung uSD card reader that you used above? I'd like to re-run my tests using this reader.
3 This is an interesting article: The best memory card readers in 2022: copy images and video to your computer


"The readers employs a fast USB 3.2 Gen 2 interface, and we clocked the CFexpress read/write speeds of 687MBs/645MBs"

 

[ScottTX]

Also this one: https://www.amazon.com/SanDisk-Extr...82139435821c9a0d8989a733eac4b2&language=en_US

 

[ScottTX]

...and one more interesting question - what is the top speed of the interface inside of our Drones?

 

[eEridani]

I'm guessing here, based on what I've read a CFexpress/UHS-II reader should be as fast as you can get for simpler uSD cards through UHS-I V90. I don't have any CFexpress nor UHS-II cards, so don't have a similar reader to test.

As for drone uSD speeds, I haven't a clue. Just what the manuals say for maximum data rate, which is 120Mb/s for the Air2, and 200Mb/s for the Mavic 3. Well below the 90MB/s rates of the cards DJI recommends.

The Samsung reader I use came with their Pro cards.

https://www.amazon.com/gp/product/B09B1HCF3H/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

 

[ScottTX]

This looks very similar to the reader that I am using:



Review: Lexar LRWM03U-7000 microSD UHS-I Card Reader USB 3.0 - Camera Memory Speed Comparison & Performance tests for SD and CF cards

 

[awraynor]

I was having issues with juddder on my MA2 using the UHS1 SanDisk Extreme Cards.
Just bought the UHS 3 Extreme Pro card to see if it fixes it, no time to fly until next
week. Great graph which may support why I'm having troubles.

 

[ScottTX]

Look forward to the results of your experiment. The other think that has been discussed is the counterfeit cards. Buy from reputable venders that control their supply chain. I deal with this professionally with with the flash memory on the Tablets that I help design.

 

[awraynor]

Look forward to the results of your experiment. The other think that has been discussed is the counterfeit cards. Buy from reputable venders that control their supply chain. I deal with this professionally with with the flash memory on the Tablets that I help design.

I had read that as well. I purchased these from Walmart as I was out of town and forget my other set. The U3 cards I just bought are from Amazon. Not sure that's any better. I ran one of the tools on the U1 card and did fair on it.

 

[eEridani]

This looks very similar to the reader that I am using:

View attachment 144403

Review: Lexar LRWM03U-7000 microSD UHS-I Card Reader USB 3.0 - Camera Memory Speed Comparison & Performance tests for SD and CF cards

According to the review it is limited to 104MB/s, similar to the Sandisk reader I have that is the same form factor.

The Samsung is a UHS-I adapter, but manages 160MB/s (or more).

 

[ScottTX]

A nice in-depth discussion of the uSD cards: just found why my 4k is jerky

Also this site: Best Memory Card for the DJI Mavic | Mavic Help