SanDisk, liars. This is NOT a microSD Class 10!

As defined by Wikipedia ([...]), the Class 10 should write to ** ** at least 10 MB / s ("que la ASSERTS Class 10 card supports 10 MB / s as a minimum non-fragmented sequential write speed. ").

This micro SD is just 8.5 MB / s ...

The proof, repeated four times. The first two tests made with the microSD / SD adapter provided by SanDisk, the other two with a microSD / USB adapter.

# Dd bs = 1M count = 1000 if = / dev / zero of = test_1000MB
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 122.091 s, 8.6 MB / s

# Dd bs = 1M count = 1000 if = / dev / zero of = test_1000MB-2
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 127.051 s, 8.3 MB / s

# Dd bs = 1M count = 1000 if = / dev / zero of = test_1000MB-3
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 147.124 s, 7.1 MB / s

# Dd bs = 1M count = 1000 if = / dev / zero of = 4-test_1000MB
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 158.018 s, 6.6 MB / s

For comparison, the same test on a truly Class 10 SD (ExtreMemory EXMESDHC32GC10 HyPerformance 32 GB SDHC Memory Card) gives 12.5 MB / s:

# Dd bs = 1M count = 1000 if = / dev / zero of = test_1000MB
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 83.7807 s, 12.5 MB / s

# Dd bs = 1M count = 1000 if = / dev / zero of = test_1000MB-2
1000 + 0 records read
1000 + 0 records written
1048576000 bytes (1.0 GB) copied, 82.862 s, 12.7 MB / s