Raspberry Pi Micro SD Cards

by jeff.cartwright.562 in Circuits > Raspberry Pi

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Raspberry Pi Micro SD Cards

micro SD cards 2.jpg

Benchmark microSD cards used in my Raspberry Pi projects.

I like to run benchmarks on the Raspberry Pi, rather than on a laptop.

The Raspberry Pi Forum Moderator wrote: "It's worth noting that the usage pattern for a Pi is drastically different to the usage pattern in a camera or camcorder. Our own NOOBS 8GB SD card is a Class 6 card and outperforms most other cards on the market in terms of system responsiveness and "real-world" use cases. The majority of Class 10 cards perform worse than Class 4 / 6 cards."

Goals:

  • Benchmark and select best micro SD card for Raspberry Pi applications

Notes:

  • text enclosed in spades, like this ♣replace-this♣ should be replaced with an actual value
  • In the Appendix, I’ve attempted to credit every source used. My apologies for any omissions.
  • $ indicates a command executed in a terminal window on the MacBook and usually is being executed on the Raspberry Pi

Gather Parts

I have these:

I bought these memory cards from Amazon, CanaKit, Fry's and so on. I use Amazon as reference price:

  • ??MB/s - SanDisk 8 GB Class 10 (UNKNOWN-8GB)
  • 30MB/s - SanDisk Ultra 16 GB microSDHC Class 6 (SDSDQY-016G-U46A) $9.81
  • 48MB/s - SanDisk Ultra 16 GB microSDHC Class 10 (SDSQUAN-016G-G4A) $8.99
  • 70MB/s - Sony 8GB Micro SDHC Class 10 UHS-1 (SR8UY2A/TQ) $7.61
  • 80MB/s - SanDisk Ultra 16GB Ultra Micro SDHC UHS-I/Class 10 (SDSQUNC-016G-GN6MA) $8.49

Create a Standard Disk_test.dmg Image

Use steps 3 and 12 in this instructable to create and save a disk test image:

Setup Raspberry Pi without Monitor or Keyboard

Use the same image on each SD card that is tested.

  • Create an image and save to the MacBook
  • For each SD card, burn the image from the MacBook to the micro SD card

Create Dd Read/Write Scripts

Initially, I ran the command line version of the dd write test five times and got three different results (12.9, 10.6 and 9.7 MB/s). So, I decided to create a script, which runs each command ten times and then calculate an average.

Open terminal window on MacBook

Login to Raspberry Pi

$ ssh pi@♣raspberry-pi-ip-address♣


Read Script

Open an editor

$ sudo nano diskreadtest.sh

and edit the file to look like:

#!/bin/bash
# disk I/O read script
for (( c=1; c<=10; c++ ))
do 
	dd if=~/test.tmp of=/dev/null bs=500K count=1024
done

Save and close

  • CTRL-o
  • ENTER
  • CTRL-x

Change the file to be executable

$ sudo chmod u+x diskreadtest.sh


Write Script

Open an editor

$ sudo nano diskwritetest.sh

and edit the file to look like:

#!/bin/bash
# disk I/O write script
for (( c=1; c<=10; c++ ))
do 
	dd if=/dev/zero of=~/test.tmp bs=500K count=1024
done

Save and close

  • CTRL-o
  • ENTER
  • CTRL-x

Change the file to be executable

$ sudo chmod u+x diskwritetest.sh

Create Hdparm Script

hdparm measures system performance as it relates to micro SD card IO

-t option shows speed of reading directly buffer cache without disk access.

-T measures how fast the drive can sustain sequential data reads, without any filesystem overhead.

Create a script that runs the command ten times to get an average.

Open terminal window on MacBook

Login to Raspberry Pi 

$ ssh pi@♣raspberry-pi-ip-address♣

Install hdparm

$ sudo apt-get install hdparm

Open an editor 

$ sudo nano hdparmtest.sh

and edit the file to look like: 

#!/bin/bash 
# hdparm script 
for (( c=1; c<=10; c++ )) 
do 
	hdparm -tT /dev/mmcblk0
done

Save and close

  • CTRL-o
  • ENTER
  • CTRL-x

Change the file to be executable 

$ sudo chmod u+x hdparmtest.sh

Run Tests on Raspberry MicroSD Cards

Open a terminal window on MacBook

Login into Raspberry Pi

$ ssh pi@♣raspberry-pi-ip-address♣

For each memory card, run the scripts (must write the file before running the read script):

Write:

$ bash diskwritetest.sh

Read

$ bash diskreadtest.sh

hdparm

$ sudo bash hdparmtest.sh

Average the results of each test and record in the Results step

Shutdown the Raspberry Pi, remove the power cord, put in the next SD card, and put the power back

$ sudo shutdown -h 0

Results

Higher is better. All SD cards are Class 10 unless otherwise noted.

UNKNOWN-8GB

  • dd read = 549.4 MB/s
  • dd write = 10.79 MB/s
  • hdparm cached reads 432.25 MB/s
  • hdparm buffered disk reads 18.16 MB/s

30MB/s, Class 6 - SanDisk SDSDQY-016G-U46A

  • dd read = 554.9 MB/s
  • dd write = 12.9 MB/s
  • hdparm cached reads 427.88 MB/s
  • hdparm buffered disk reads 18.17 MB/s

48MB/s - SanDisk SDSQUAN-016G-G4A

  • dd read = 552.5 MB/s
  • dd write = 15.38 MB/s
  • hdparm cached reads 428.96 MB/s
  • hdparm buffered disk reads 18.09 MB/s

70MB/s - Sony SR8UY2A/TQ

  • dd read = 555 MB/s
  • dd write = 16.53 MB/s
  • hdparm cached reads 430.35 MB/s
  • hdparm buffered disk reads 16.87

80MB/s - SanDisk SDSQUNC-016G-GN6MA

  • dd read = 553.9 MB/s
  • dd write = 12.61 MB/s
  • hdparm cached reads = 428.45 MB/s
  • hdparm buffered disk reads = 15.65 MB/s

32GB USB Drive (unknown make/model - used as main drive)

  • dd read = 512.3 MB/s
  • dd write = 14.27 MB/s
  • hdparm cached read = 408.96 MB/s
  • hdparm buffered disk reads = 17.98 MB/s

Appendix - References

I used these sources in writing this instructable