How can I test SD card speed?

[mpalomer]

I want to see how fast my SD card operates on the Raspberry Pi. How do I do this? Also, in your experience, what's the fastest card out there? I'm not doing anything that needs a lot of storage, so anything as low as 4GB would be fine with me.

[pluggy]

http://elinux.org/RPi_SD_cards#SD_card_performance

On this page is the 'official' way.

Write :

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dd if=/dev/zero of=~/test.tmp bs=500K count=1024

Read

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dd if=~/test.tmp of=/dev/null bs=500K count=1024

With most operating systems and uses, read speed is far more important than write speed. But you need to run the write test first since it creates a file used in the read test.

[Amarand]

http://elinux.org/RPi_SD_cards#SD_card_performance

On this page is the 'official' way.

Write :

Code: Select all

dd if=/dev/zero of=~/test.tmp bs=500K count=1024

Read

Code: Select all

dd if=~/test.tmp of=/dev/null bs=500K count=1024

With most operating systems and uses, read speed is far more important than write speed. But you need to run the write test first since it creates a file used in the read test.

It's super important to do this (listed on that link above) after the write and before the read:

sync; echo 3 | sudo tee /proc/sys/vm/drop_caches

If you don't, then you'll hit cache and may see speeds like this:

524288000 bytes (524 MB) copied, 0.998347 s, 525 MB/s

Rather than this:

524288000 bytes (524 MB) copied, 27.8044 s, 18.9 MB/s

Hope that helps!

[tonyawad88]

Thank you these scripts helped.

[cmoriarty]

It looks like there is a parameter you can pass to dd "oflag=dsync" to disable caching.

oflag=dsync (oflag=dsync) : Use synchronized I/O for data. Do not skip this option. This option get rid of caching and gives you good and accurate results

source : https://www.cyberciti.biz/faq/howto-lin ... d-command/