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I currently have the previous raspberry pi class 4 card. I'm considering getting the new raspberry pi model 2 class 10 card. Is there a speed difference between the two cards?

Mike Poole
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3 Answers3

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Somewhat contra Jivings and Jacobm001, here's a test of two particular cards (class 4 and class 10) I did when I first got a pi:

Benchmarking SD cards, read speed is identical

There is a link there to anecdotal results from other people doing the same kind of test with various cards. Obviously on average class 10 cards are better but the max read speed of the SD card reader on the pi is 25 MB/s, regardless of how fancy a card you get. I believe both class 4 and class 10 are capable of this.

If you are already getting 20 MB/s read, that is something to keep in mind. Again, a class 10 will be better and is probably worth the few bucks in price difference.

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goldilocks
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    An actual class 4 card is only good for 4 MB/s. A UHS class of four would be 40 MB/s iirc. – Jacobm001 Jan 14 '16 at 17:35
  • @Jacobm001 Do you have a reference for that? Is that a minimum? I am certainly not the only one to report a read speed of 15-20 MB/s with a class 4 card and it is hard to see a flaw in that test method. – goldilocks Jan 14 '16 at 17:39
  • Also, as per Patrick Cook's answer, perhaps read and write times are getting confused here. – goldilocks Jan 14 '16 at 17:42
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    https://www.sdcard.org/developers/overview/speed_class/ – Jacobm001 Jan 14 '16 at 18:19
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    @Jacobm001 That is exactly my point: "Speed Class designates minimum writing performance to record video." -> Emphasis on "minimum" and "writing". It does not say those numbers apply to reads, or represent an upper limit. I see the telephone game at work here ;) – goldilocks Jan 14 '16 at 18:20
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The difference between the class 4 and class 10 would be extremely obvious on the original RPi, and even more so on the RPi 2.

Even if you're using a read only filesystem, the boot time will be dramatically shorter.

Jacobm001
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  • Class 10 cards have a faster write speed, but almost always this comes with slower read speeds. It shouldn't effect the Pi too much though. – Patrick Cook Jan 14 '16 at 17:41
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The class of a Micro SD card determines it's write time, NOT it's read time. Class 10 cards usually have a slower read time than Class 4 cards. Class 4 has a fast enough read and write speed for most everything the Pi does, Class 10 cards can have slower boot times, but you should be fine with either.

Source: https://www.sdcard.org/developers/overview/speed_class/

Patrick Cook
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