I am Writing log files to an usb-memory using MFS and the usb-host stack in MQX 4.2. The files are 1.6Mb each. The tests are performed on a TWR-KF120 board using Sandisk Cruzer Blade 8GB usb-memories.
It starts out pretty good with a write speed of about 500kB/s. However, the performance degrades to half after a couple of hundred files and after like 1000 files it is down to 40kB/s. Is this normal? It seems to me that MFS gets very slow when the usb-memory starts to fill up.