After upgrade from 6.6.6 stable to 6.7.0-rc2 I see unusual reads whenever I write to a single disk.
E.g. In this example I write/copy to \\tower2\disk21 from my Windows 10 machine (SMB). During the whole copy all other disks are spun up and are read at low speed. In the example shown in the picture a 40GB file is written. disk21 and parity/parity2 show the usual write activity. But the other disks are spun up and read as well.
After the file is written reading the other disks stopps as well.
Diagnostics and image attached.
*** Edit: The Main page shows that same read activity for the flash drive as well. Forgot to mention that.