Same here
I have a ZFS pool with 4 HDD WD40EFRX in raidz1 connected to ATA 2, 3, 4 and 5
At the first time I performed a scrub I got a degraded pool with a disk faulted. The faulted disk can vary, usually between ata 3, 4 of 5 but (so far) never ata 2.
Forcing sata to 3.0 did not solve this issue for me.
I'll appreciated any advice on this