MicroSD Card versus USB Flash Drive for Raspberry Pi 2

Question

Articles on this topic from 2012 for earlier RPi hardware extolling the virtues of using an external USB flash drive are now dated.

In 2015, using Raspberry Pi 2 hardware, is there still any advantage to moving the root file system and booting from an external USB flash drive instead of just using the default microSD card?

Solution 1

My DriveSpeed benchmark measures speed of large and small file writes and reads, plus random writing and reading. RPi 2 results for SD and USB drives are here.

http://www.roylongbottom.org.uk/Raspberry%20Pi%20Benchmarks.htm#anchor21

For booting, you need to establish which performance feature is more important and it is not just large file data transfer speed. Anyway, it mainly depends on the drive hardware performance characteristics. My system SD card can be out performed by SD cards in a USB card reader.

Solution 2

I'm not sure if the raspberry pi bootloader is even capable of booting from USB, but I could be mistaken (there might be a way to set up an SD card to act as an intermediate step in mounting the OS from USB).

Aside from that, I can't imagine you'll notice much of a speed difference between the micro sd and a USB 2 flash drive (as far as I'm aware, the rpi doesn't have usb 3 hardware). Both will have similar life span.

Other considerations: power consumption (I believe SD has an advantage here, especially since a card will have to be used anyway to boot), quality of either device (you can buy really bad SD cards and USB flash drives alike)

I would be interested in seeing some bench marks if you decide to run any tests to see if there's a difference.