What is faster?

External or internal sdcard?

External - ext4 class10

"class10" doesn't mean anything, unless your using a 'camera'...

Find out for yourself:
http://lwn.net/Articles/428584/
https://git.linaro.org/gitweb?p=people/arnd/flashbench.git;a=summary

Regards,

OK, What is faster: external or internal sdcard on BeagleBone Black?

"only" you can answer that, as "only" you know what "external" media
you have placed in the BBB... Benchmark both devices and find out..

Regards,

OK, With which parameters an sdcard must be so that it would be faster than internal sdcard?))

(if class means nothing, what mean then?)

The "class" rating assumes a "fat32" partition and dumping "large"
linear images from a camera sensor to a drive.

It has nothing to do with the type of loads you see when running linux
on the drive, which are mostly random...

More details: (including class 4 cards beating class 6/10)
https://wiki.linaro.org/WorkingGroups/Kernel/Projects/FlashCardSurvey

Regards,

If you want something to compare to, the eMMC on the beaglebone black
tests as [1] and [2]. Find an SD card that can do better than that.
Good SD cards should be able to beat the internal eMMC on open-au and
write speeds but reads are going to be difficult to beat. If your
workload is mostly reads, just use the eMMC, it's fast and high quality.

[1]:http://lists.linaro.org/pipermail/flashbench-results/2013-January/000353.html
[2]:http://lists.linaro.org/pipermail/flashbench-results/2013-February/000355.html

If you want a decent microSD card, go buy a Samsung Plus series card,
they're quite good.

-Andrew