64GB Ultra Fit slower than 32GB Ultra Fit

Hi,

I’m not using windows but a unix-like OS.
Into identical machines, into their usb2 port (no usb3 here), I find that the 64GB Ultra Fit version is quite a lot slower than the 32GB version. Why is this?

dmesg identifies them differently.
These two usb thumb drives with identical packaging apart from the size listing.

32GB: (bought late 2020 from amazon)
sd0 at scsibus0 targ 1 lun 0: <USB, SanDisk 3.2Gen1, 1.00>
sd0: 29340MB, 512 bytes/sector, 60088320 sectors

64GB: (bought last year, also amazon)
sd0 at scsibus0 targ 1 lun 0: <SanDisk, Ultra Fit, 1.00>
sd0: 58680MB, 512 bytes/sector, 120176640 sectors

write test for the 32GB stick, 1MB block size:

$ date && dd if=/dev/urandom of=test.bin bs=1m count=500 && date
Sun Dec 11 01:41:08 GMT 2022
500+0 records in
500+0 records out
524288000 bytes transferred in 198.821 secs (2636983 bytes/sec)
Sun Dec 11 01:44:27 GMT 2022

64GB:

$ date && dd if=/dev/urandom of=test.bin bs=1m count=500 && date
Sun Dec 11 01:38:11 GMT 2022
500+0 records in
500+0 records out
524288000 bytes transferred in 370.088 secs (1416655 bytes/sec)
Sun Dec 11 01:44:22 GMT 2022

about 54% of the speed of the 32GB

32GB with block size = cluster size

$ date && dd if=/dev/urandom of=test3.bin bs=512 count=1024000 && date
Sun Dec 11 05:18:07 GMT 2022
1024000+0 records in
1024000+0 records out
524288000 bytes transferred in 266.413 secs (1967946 bytes/sec)
Sun Dec 11 05:22:33 GMT 2022

64GB:

$ date && dd if=/dev/urandom of=test3.bin bs=512 count=1024000 && date
Sun Dec 11 05:17:45 GMT 2022
1024000+0 records in
1024000+0 records out
524288000 bytes transferred in 329.442 secs (1591438 bytes/sec)
Sun Dec 11 05:23:15 GMT 2022

it’s 80% of the speed of the 32GB

Hi @swift.gate9914,

Have you opened a Support Case? If not opened, for more information, please contact the SD Technical Support team for best assistance and troubleshooting:
https://kb.sandisk.com/app/ask