Raspberry PI Storage Performance: Part 2 U3 vs U3 Cards, they are all no equal

In the previous post in this short series, I shared a benchmark between MicroSD card and a USB Drive. In this review we look at two different MicroSD cards, both with a U3 rating.


The U3 rated card was used in the previous test, a ScanDisk Ultra card.

Performance on this card was  21.0 MB/s on read, and  17.2 MB/s on the write, with about  .47 Msec latency on average. Performance was not stable though, with the card starting to degrade in through towards the end of the test, dropping to under 12 MB/s on reads and writes.



The second U3 card ( tested two different cards) came from Microcenter, their store branded card.



With this card, Average read was 11.6 MB/s and 10.4 MB/s write, with .74 msec latency average. Performance on this card was significantly less, with some latency hitting almost 2 ms, and write throughput dropping to under 4MB/s at times.


This shows the biggest risk using MicroSD cards, the quality of the cards. Even though two cards have the same rating, performance is a huge roll of the dice. For both brands, I tested with two cards, and the results were comparable between brands. When running on a PI, research the brand, and make sure you get a card that performs as promised.