A Mac with homebrew installed.
An SD card with (ideally) nothing on it.
Step 1. Launch Terminal
.
Step 2. Paste this command into Terminal
(it's from the homebrew site here.)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
Enter your password if it asks you to, it will take a moment or two to install. You can verify you installed brew properly after by typing brew, and it'll give you a list of commands/arguments you can use.
Step 1. Launch Terminal
and install F3 with brew using the command below.
brew install f3
Step 1. Launch Disk Utility
so we can find out what Volume your SD card is.
If you haven't already, select the drop down tab in the top left of Disk Utility
, and select Show All Devices
.
Step 2. Select your Volume on your SD card. Note down the reported mount point, in my case it shows up as /Volumes/TEST NX
.
Step 3. Tab back into Terminal (or launch it again if you closed it.) Type out f3write "/Volumes/[YOUR VOLUME HERE]"
, hit enter for it to start. This will take a bit depending on the size and speed of your SD card. Make sure to include the brackets.
Once it's done F3 will tell you the average write speed and your Terminal
should look something similar like this (or possibly more parts, if your card was larger than mine.)
Step 4. Tab back into Terminal
(or launch it again if you closed it.) Type out f3read "/Volumes/[YOUR VOLUME HERE]"
, hit enter for it to start. This will take a bit depending on the size and speed of your SD card. Make sure to include the quotation marks.
Once finished, your results should look similar like the above image if your card isn't corrupt and is fine. If the utility detects corruption, you can try formatting your card as FAT32 with Disk Utility
, and then test it once more. But your card most likely is failing, or faulty.
You may also now delete the hardware test files the command line utility made on your SD card, make sure your empty your Mac's Trash after too.