According to the getting started: https://www.home-assistant.io/getting-started/
You recommend A2 microSD in Raspberry Pi 4.
However, all tests I’ve seen fail to give a better performance to A2 over A1, due to the lack of A2 microSD support in Raspberry Pi:
I think the recommendation is based on handling of wear over time, not speed. I seem to recall some discussion awhile back that the A2 cards were better at handling the repetitive reads and writes.
I need to agree with jd here.
All rpi threads I’ve come across discourage using A2 - most probably because Linux doesn’t support the special command set needed to reach the (falsely?) advertised IOPS:
Application Performance Class 2 (A2)
Cache and Command Queuing require host (driver) support since the host needs to activate those new features first . The cache feature on A2 rated cards makes use of volatile RAM on the card requiring the host to learn new commands to issue flushing the cache (involving the risk of data losses – for details see especially chapter 4.17 in Physical Layer Simplified Specification 6.0)
https://www.raspberrypi.org/forums/viewtopic.php?t=224631
If you follow ^ to the source of the information on github, you will find that A2 cards are actually much slower than similarly-named A1 “predecessors” - which probably explains the harsh words A2 has received here: https://www.raspberrypi.org/forums/viewtopic.php?t=245885