The storage node software is a best testing suite in this case, but not portable unfortunately (except connecting this disk to a bare metal Windows).
Synthetic tests likely would not give you the answer, or you need to test simultaneous random reads and writes with sizes around 2MiB with something like 1. fio - Flexible I/O tester rev. 3.36 — fio 3.36 documentation
I didn’t find on the forum a profile for storagenode though, except
but it’s likely not representative, because block size on NTFS is actually 4k, not 128k and they also tested only writes, but I assume that you have a problem mostly with reads.