Choosing micro SD card for Raspberry Pi 4

So I have a new Pi 4 on hand, should I plug in an used 8GB micro SD card?


Well, I want to test the performance of the new pi, so let's not let the old SD card becomes the bottle neck!

Short answer:

At minimum, get a 16 GB card with A1 speed. 
I'd just add few more bulks to get a 32 GB with V30.

Been away from the card standards for a while, my last knowledge was class 10, U1, etc.

What is A1?  V10?  V30?

Simple enough, 'A' means Application, good for mobile phone to run application directly from, instead of old usage only storing data.

Now, if you guess 'V' for Video, you are correct!

V30 is good for 4K video recording without dropping frames.  That V30 has higher writing speed (~100MB/s) than A1 standard.

Some said for a pi 3, use at least an A1, which meets the the standard of certain IOPS, unit of random performance, the number of random access I/O operations in one second.  V30 preferred on Pi 4.