There is no command queue in write through mode. The write data is directly written to the HDD and also stored it in the cache memory. The small test stream size only sustains to one or two HDDs each time. That’s why the write performance is at 224.3 MB/s. The read data comes from the cache that its fast speed is out of the Blackmagic exceptation. Blackmagic will consider it as no read cycle happens. That’s why the read performance is 0 MB/s.