sd

 ____________________________________________
/ Fool me once, shame on you. Fool me twice, \
\ prepare to die. (Klingon Proverb)          /
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        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

(Excerpt from Ansible for DevOps, chapter 12.)

The fallout from this year's microSD card performance comparison has turned into quite a rabbit hole; first I found that new 'A1' and 'A2' classifications were supposed to offer better performance than the not-Application-Performance-class-rated cards I have been testing. Then I found that A2 rated cards offer no better performance for the Raspberry Pi—in fact they didn't even perform half as well as they were supposed to, for 4K random reads and writes, on any hardware I have in my possession.

Update: See follow-up post about A1 vs A2 performance, Raspberry Pi microSD follow-up, SD Association fools me twice?.

After I published my 2019 Raspberry Pi microSD card performance comparison, I received a lot of feedback about newer 'A2' Application Performance class microSD cards, and how they could produce even better performance for a Raspberry Pi.

None of these cards are fakes; grainy halftone printing is visible because I shot this with a macro lens.

Since I'm running a Mac, and don't have a spare linux-running machine that can mount ext4-formatted partitions (like those used by default for official Raspberry Pi distributions like Raspbian on SD cards), I don't have a simple way to mount the boot partition on my Mac to tweak files on the Pi; this is a necessity if, for example, you break some critical configuration and the Pi no longer boots cleanly.

To mount an ext4-formatted SD or microSD card on a Mac, the easiest option is to use VirtualBox (and, in my case, Vagrant with one of Midwestern Mac's Ubuntu boxes). Boot a new linux VM (any kind will do, as long as it's modern enough to support ext4), shut it down, go into Settings for the VM inside VirtualBox and enable USB, then reboot.

Follow these steps once the VM is booted, to mount the flash drive: