If I go on https://www.sdcard.org/developers/sd-standard-overview/application-performance-class/
A class 1 (A1) card is specified by 1500 IOPs minimum random read and 500 IOPs minimum random write
A class 2 (A2) card is pecified by 4000 IOPs minimum random read and 2000 IOPs minimum random write
I started with a 128gb Evo Plus (white) but I am totally confused by the A2 rating due to what even a generic A1 from mymemory can provide.
Here is the 32gb Mymemory generic A1
[Read]
SEQ 4KiB (Q= 8, T= 1): 11.049 MB/s [ 2697.5 IOPS] < 2961.29 us>
SEQ 4KiB (Q= 1, T= 1): 9.881 MB/s [ 2412.4 IOPS] < 413.64 us>
RND 4KiB (Q= 32, T= 1): 7.464 MB/s [ 1822.3 IOPS] < 17518.72 us>
RND 4KiB (Q= 1, T= 1): 6.534 MB/s [ 1595.2 IOPS] < 625.05 us>
[Write]
SEQ 4KiB (Q= 8, T= 1): 4.771 MB/s [ 1164.8 IOPS] < 6855.69 us>
SEQ 4KiB (Q= 1, T= 1): 4.964 MB/s [ 1211.9 IOPS] < 824.34 us>
RND 4KiB (Q= 32, T= 1): 4.675 MB/s [ 1141.4 IOPS] < 27938.02 us>
RND 4KiB (Q= 1, T= 1): 3.966 MB/s [ 968.3 IOPS] < 1030.37 us>
Here is a EvoPlus 128gb (white) A2
[Read]
SEQ 4KiB (Q= 8, T= 1): 13.969 MB/s [ 3410.4 IOPS] < 2326.91 us>
SEQ 4KiB (Q= 1, T= 1): 12.428 MB/s [ 3034.2 IOPS] < 329.03 us>
RND 4KiB (Q= 32, T= 1): 11.271 MB/s [ 2751.7 IOPS] < 11601.40 us>
RND 4KiB (Q= 1, T= 1): 10.004 MB/s [ 2442.4 IOPS] < 408.77 us>
[Write]
SEQ 4KiB (Q= 8, T= 1): 3.386 MB/s [ 826.7 IOPS] < 9657.65 us>
SEQ 4KiB (Q= 1, T= 1): 3.272 MB/s [ 798.8 IOPS] < 1248.77 us>
RND 4KiB (Q= 32, T= 1): 3.508 MB/s [ 856.4 IOPS] < 37161.91 us>
RND 4KiB (Q= 1, T= 1): 3.205 MB/s [ 782.5 IOPS] < 1274.52 us>
Not only does it not meet A2 spec its considerably slower on random writes than a A1 card?
So that got me thinking maybe this card isn't bonfied and I purchased a EvoProPlus 128gb that comes with a samsung usb 3.0 card reader.
Here is a EvoProPlus 128gb (blue) A2
[Read]
SEQ 4KiB (Q= 8, T= 1): 13.458 MB/s [ 3285.6 IOPS] < 2431.09 us>
SEQ 4KiB (Q= 1, T= 1): 11.470 MB/s [ 2800.3 IOPS] < 356.44 us>
RND 4KiB (Q= 32, T= 1): 10.843 MB/s [ 2647.2 IOPS] < 12041.19 us>
RND 4KiB (Q= 1, T= 1): 10.640 MB/s [ 2597.7 IOPS] < 384.47 us>
[Write]
SEQ 4KiB (Q= 8, T= 1): 3.261 MB/s [ 796.1 IOPS] < 10015.06 us>
SEQ 4KiB (Q= 1, T= 1): 3.081 MB/s [ 752.2 IOPS] < 1326.09 us>
RND 4KiB (Q= 32, T= 1): 3.172 MB/s [ 774.4 IOPS] < 41072.57 us>
RND 4KiB (Q= 1, T= 1): 3.137 MB/s [ 765.9 IOPS] < 1301.98 us>
Neither of the cards seem to meet A2 specs but I am even more confused for random writes they are even slower than a generic A1!?
The above was used the samsung supplied with the evo pro card reader windows 10 usb3
Am I doing something wrong with the format of these cards as I am totally confused at the results I seem to be getting.
Surely an A2 card for random writes can not be considerabilly slower than an A1 card?
