Very Slow Flash Memory Card Random Seek + RW Speed

[qinghuiz]

I ran a disk test on a SD card using PerformanceTest 6.1 and got the following results:

Disk Sequential Read: 6.4 MBytes/Sec
Disk Sequential Write: 2.56 MBytes/Sec
Disk Random Seek +RW: 0.16 MBytes/Sec

I can understand write is a little bit slower than read with memory card, but the random seek + RW speed is too much slower than I expect. I expect the random seek + RW should be close to the sequential RW with memory card, as it does not have disk head mechanical movement. Do you know why?

[David (PassMark)]

The seek test involves seeking plus some reading and writing. The seek would effectively take zero time on a SD card, but the performance on non sequential writes is what is bringing it down.

Random writes are really really slow on many of these Flash cards. (But the newer ones are improving).

[qinghuiz]

Thanks for your quick response!

How about the random read speed with flash memory? And how to test the random read only speed? It seems that the random +RW test does not separate read and write test.

[David (PassMark)]

Use the advanced disk test option. You can select read only, write only, or both, with sequential or random access. Plus much more.