Troubleshooting MicroSD Card Performance and Recommended MicroSD Cards

We recommend SanDisk and Samsung cards with A2 or A1 rating. Make sure that it is “Sold by Amazon.com” or else it could be a fake card.

Recommended A2 Rated Cards:

  1. SanDisk Extreme
  2. Samsung Pro Plus
  3. Samsung Evo Plus (64GB is A1)

Recommended A1 Rated Cards:

  1. SanDisk Ultra
  2. Samsung Evo Select

We do not recommend any other manufacturer because they have consistently proven themselves to put out unreliable products.

Our images are designed to detect silent MicroSD card corruption and lengthen MicroSD card life.

  1. If you suspect data corruption, run sudo dmesg | grep mmc and look for errors. Feel free to post your output below if you are not sure what counts as an error.
  2. To test read speed, run sudo dd if=$(findmnt -nvo SOURCE /) of=/dev/null bs=1M status=progress. Press Control+C to end. If this drops below 20MB/s, we recommend another card.
  3. To test write speed, run openssl enc -aes-128-ctr -pass pass:"$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt < /dev/zero | dd of=test.file iflag=fullblock oflag=direct bs=1M status=progress. Press Control+C to end. If this drops below 15MB/s, we recommend another card.